Practitioner blog about Claude Code: hooks, subagents, MCP, skills, CLAUDE.md. Every post ships with the JSON, the timings, and the failure modes from real use.https://agentcookbooks.com/enWed, 03 Jun 2026 00:00:00 GMThttps://agentcookbooks.com/blog/ai-hallucinated-concrete-detail/https://agentcookbooks.com/blog/ai-hallucinated-concrete-detail/A give-concrete-detail brand-voice line made a content pipeline invent unverifiable specifics. Fix: a context constraint, a [FILL] channel, a banned list.Wed, 03 Jun 2026 00:00:00 GMTclaude-codeagent-reliabilitycontext-engineeringhttps://agentcookbooks.com/blog/compliance-as-precommit-rules/https://agentcookbooks.com/blog/compliance-as-precommit-rules/Eighteen pre-commit rules encode GDPR, consumer-protection, and thin-content checks as compliance-as-code — ~150ms per commit, blocking commits, not launch.Wed, 03 Jun 2026 00:00:00 GMTclaude-codehookscompliancehttps://agentcookbooks.com/blog/custom-subagents-autonomous-delegation/https://agentcookbooks.com/blog/custom-subagents-autonomous-delegation/Five domain-scoped .claude/agents/ subagents, each with its own restricted tool list and per-agent pre-commit skip-list, delegated by description not by name.Wed, 03 Jun 2026 00:00:00 GMTclaude-codesubagentsagentshttps://agentcookbooks.com/blog/markitdown-19mb-pdf-webfetch-limit/https://agentcookbooks.com/blog/markitdown-19mb-pdf-webfetch-limit/WebFetch caps fetches at 10MB, so a 19.5MB system-card PDF stayed unread. MarkItDown converted it in 66s — and recovered the number we couldn't verify.Sun, 31 May 2026 00:00:00 GMTclaude-codedocumentationcontext-engineeringhttps://agentcookbooks.com/blog/asr-llm-double-failure-agent-memory/https://agentcookbooks.com/blog/asr-llm-double-failure-agent-memory/Each layer was fine alone. Stacked, ASR and an LLM classifier wrote a grammatically valid false fact the agent stated on every call. The audit that catches it.Fri, 29 May 2026 00:00:00 GMTclaude-codeagentshttps://agentcookbooks.com/blog/cloudflare-pages-purge-cache-after-deploy/https://agentcookbooks.com/blog/cloudflare-pages-purge-cache-after-deploy/A Cache Rule makes Cloudflare Pages edge-cache HTML, so your next deploy stays invisible at the canonical URLs for up to 24h — until you purge.Fri, 29 May 2026 00:00:00 GMTclaude-codedeploymenthttps://agentcookbooks.com/blog/gsc-crawled-not-indexed-noindex-alternates/https://agentcookbooks.com/blog/gsc-crawled-not-indexed-noindex-alternates/22 URLs hit Search Console's 'Crawled – currently not indexed' — all noindex'd markdown alternates. When that bucket is your noindex working, not a defect.Fri, 29 May 2026 00:00:00 GMTclaude-codeseohttps://agentcookbooks.com/blog/notion-api-four-production-gotchas/https://agentcookbooks.com/blog/notion-api-four-production-gotchas/A Notion sync layer that read clean in the docs broke four ways in prod: UTF-16 rich_text limits, appending template enums, orphan writes, and a schema split.Fri, 29 May 2026 00:00:00 GMTclaude-codeapihttps://agentcookbooks.com/blog/opus-4-8-dynamic-workflows-fact-check/https://agentcookbooks.com/blog/opus-4-8-dynamic-workflows-fact-check/We run Opus 4.8 with Ultracode (xhigh + Dynamic Workflows), so we aimed it at the launch claims: 15 agents, ~1.1M tokens, 3 of 32 claims refuted.Fri, 29 May 2026 00:00:00 GMTclaude-codesubagentscost-managementhttps://agentcookbooks.com/blog/astro-sitemap-doesnt-filter-noindex-pages/https://agentcookbooks.com/blog/astro-sitemap-doesnt-filter-noindex-pages/24 noindex topic pages plus /404/ were leaking into sitemap-0.xml. The filter callback that drops them, and the .mjs-can't-import-.ts gotcha.Tue, 26 May 2026 00:00:00 GMTclaude-codeseohttps://agentcookbooks.com/blog/cloudflare-pages-html-cache-the-missing-rule/https://agentcookbooks.com/blog/cloudflare-pages-html-cache-the-missing-rule/The _headers Cache-Control directive worked for /_astro/ assets but not HTML. The Cache Rule that fixed it, the UI gotcha, curl MISS-then-HIT.Tue, 26 May 2026 00:00:00 GMTclaude-codedeploymenthttps://agentcookbooks.com/blog/elevenlabs-conversational-ai-four-200-ok-footguns/https://agentcookbooks.com/blog/elevenlabs-conversational-ai-four-200-ok-footguns/Four ElevenLabs Conversational AI gotchas that return 200 OK with wrong behavior: workspace-scoped keys, hidden override toggles, dual webhook auth, test gates.Tue, 26 May 2026 00:00:00 GMTclaude-codedeploymenthttps://agentcookbooks.com/blog/astro-jsonld-slot-head-nested-drop/https://agentcookbooks.com/blog/astro-jsonld-slot-head-nested-drop/Moved BreadcrumbList JSON-LD into a nested Astro component's slot=head. It vanished. Search Console: 0 items. The undocumented Astro slot rule.Mon, 25 May 2026 00:00:00 GMTclaude-codeseohttps://agentcookbooks.com/blog/gcp-budget-doesnt-cap-pubsub-killswitch/https://agentcookbooks.com/blog/gcp-budget-doesnt-cap-pubsub-killswitch/GCP budgets are alert-only. Pub/Sub → Cloud Function → updateBillingInfo is the real kill-switch — plus the Gen 2 logger gotcha that ate an afternoon.Mon, 25 May 2026 00:00:00 GMTclaude-codedeploymentcost-managementhttps://agentcookbooks.com/blog/playwright-pdf-replace-weasyprint-five-footguns/https://agentcookbooks.com/blog/playwright-pdf-replace-weasyprint-five-footguns/Migrating five PDF formats off WeasyPrint to Playwright + Chromium worked — after the asyncio deadlock, the systemd sandbox, and the per-user browser cache.Mon, 25 May 2026 00:00:00 GMTclaude-codedeploymenthttps://agentcookbooks.com/blog/claude-code-plugin-anatomy/https://agentcookbooks.com/blog/claude-code-plugin-anatomy/What ships in a Claude Code plugin: 12-line marketplace.json, 12-line plugin.json, no enumeration. Discovery is directory-based.Sun, 24 May 2026 00:00:00 GMTclaude-codeskillscookbookcodebase-analysishttps://agentcookbooks.com/blog/cloudflare-pages-six-failures-before-headers/https://agentcookbooks.com/blog/cloudflare-pages-six-failures-before-headers/First Astro 6 deploy to Cloudflare Pages: 6 failed builds, 2 rollbacks, 8 commits, 8 hours. The ordered list of fails the docs scatter across six pages.Sun, 24 May 2026 00:00:00 GMTclaude-codedeploymenthttps://agentcookbooks.com/blog/claude-code-sessionstart-systemmessage-vs-additionalcontext/https://agentcookbooks.com/blog/claude-code-sessionstart-systemmessage-vs-additionalcontext/Wrote a SessionStart hook to surface open work. systemMessage shows it in the UI; additionalContext injects it into model context.Sat, 23 May 2026 00:00:00 GMTclaude-codehookshttps://agentcookbooks.com/blog/cloudflare-email-protection-screen-reader-trap/https://agentcookbooks.com/blog/cloudflare-email-protection-screen-reader-trap/A11y audit on the live homepage caught a Cloudflare edge-side trick that source-code audits can't see: the footer email link reads 'email protected' aloud.Sat, 23 May 2026 00:00:00 GMTclaude-codea11yhttps://agentcookbooks.com/blog/fewer-permission-prompts-scanned-15-sessions-one-allowlist-line/https://agentcookbooks.com/blog/fewer-permission-prompts-scanned-15-sessions-one-allowlist-line/Scanned 15 Claude Code session transcripts for prompts to allowlist. ~50 commands extracted, one strict survivor. The auto-allow list is broader than expected.Thu, 21 May 2026 00:00:00 GMTclaude-codeharnesshttps://agentcookbooks.com/blog/pytrends-keyword-research-12-queries-before-429/https://agentcookbooks.com/blog/pytrends-keyword-research-12-queries-before-429/Google Trends keyword research with pytrends: the urllib3 method_whitelist trap, a 429 on the 13th query, and two findings that flipped the plan.Thu, 21 May 2026 00:00:00 GMTclaude-codeseohttps://agentcookbooks.com/blog/scheduled-remote-agents-cant-see-gitignored-files/https://agentcookbooks.com/blog/scheduled-remote-agents-cant-see-gitignored-files/Three /schedule routines proposed, two created, one declined. The recurring sweep would have read a gitignored folder — the remote agent can't see those.Thu, 21 May 2026 00:00:00 GMTclaude-codeautomationhttps://agentcookbooks.com/blog/customer-research-on-a-pre-launch-blog/https://agentcookbooks.com/blog/customer-research-on-a-pre-launch-blog/Ran /customer-research with no customer assets and no G2 reviews. Mode 1 and Mode 2 both partly failed; the confidence-levels guardrail saved the run.Mon, 18 May 2026 00:00:00 GMTclaude-codemarketingstrategyresearchhttps://agentcookbooks.com/blog/seo-schema-validates-but-wont-extend/https://agentcookbooks.com/blog/seo-schema-validates-but-wont-extend/Ran /seo-schema against a site that already emits five schema types. It validates cleanly, won't help you add the next one — and that's a tell.Mon, 18 May 2026 00:00:00 GMTclaude-codeseohttps://agentcookbooks.com/blog/eeat-audit-anonymity-policy-as-authority-ceiling/https://agentcookbooks.com/blog/eeat-audit-anonymity-policy-as-authority-ceiling/E-E-A-T audit, 197 skills + 20 blog posts on anonymous wiki. Authority caps at ~5/10 by policy. Experience-on-display is the real defect — three fixes shipped.Sun, 17 May 2026 00:00:00 GMTclaude-codeauditseohttps://agentcookbooks.com/blog/twenty-broken-links-three-upstream-restructures/https://agentcookbooks.com/blog/twenty-broken-links-three-upstream-restructures/Site-wide link audit on a static Astro wiki: 12,753 hrefs across 311 pages, 20 broken externals. Root cause: three upstream repos restructured the same week.Sun, 17 May 2026 00:00:00 GMTclaude-codeauditseohttps://agentcookbooks.com/blog/competitor-profiling-named-a-competitor-i-didnt-know-existed/https://agentcookbooks.com/blog/competitor-profiling-named-a-competitor-i-didnt-know-existed/A profiling skill sized for Firecrawl + DataForSEO, run without either. The discoverability step it skipped is where the actual finding landed.Tue, 12 May 2026 00:00:00 GMTclaude-codeskillspositioninghttps://agentcookbooks.com/blog/one-dispatch-160-files-classified-the-rubric-was-the-bug/https://agentcookbooks.com/blog/one-dispatch-160-files-classified-the-rubric-was-the-bug/Dispatched an Explore agent to classify 160 wiki entries. The rubric the agent invented mapped to a phrase that appears in 142 of those files.Tue, 12 May 2026 00:00:00 GMTclaude-codeskillssubagentshttps://agentcookbooks.com/blog/verification-half-the-audit-claims-werent-greppable/https://agentcookbooks.com/blog/verification-half-the-audit-claims-werent-greppable/Ran evidence-before-assertion on a four-claim audit. Two passed grep. The other two were the agent's content read, accepted on trust.Tue, 12 May 2026 00:00:00 GMTclaude-codeskillsevalshttps://agentcookbooks.com/blog/breadth-to-depth-pausing-wiki-imports-at-12-sources/https://agentcookbooks.com/blog/breadth-to-depth-pausing-wiki-imports-at-12-sources/Wiki at 160 skills: 14 firsthand, 9 visibly TODO, 137 still-generic. Pausing new imports. Two moves earn more leverage: real engagements and cookbook posts.Sat, 09 May 2026 00:00:00 GMTclaude-codeskillseditorialhttps://agentcookbooks.com/blog/cloudflare-pages-html-cache-week-one-449-visitors/https://agentcookbooks.com/blog/cloudflare-pages-html-cache-week-one-449-visitors/First seven days post-domain-attach: 449 visitors, 8.7 requests per visit, 5.99% cache rate. GPTBot spiked +3,763%. Three hypotheses, one already confirmed.Sat, 09 May 2026 00:00:00 GMTclaude-codedeploymentanalyticshttps://agentcookbooks.com/blog/meta-description-sprawl-one-helper-fixes-142-pages/https://agentcookbooks.com/blog/meta-description-sprawl-one-helper-fixes-142-pages/An n=8 sample flagged one over-long meta description on this Astro wiki. The full 153-skill sweep showed 142. One helper in Base.astro fixed all of them.Sat, 09 May 2026 00:00:00 GMTclaude-codeseoastrohttps://agentcookbooks.com/blog/parallel-session-gitignore-trap-two-destructive-ops/https://agentcookbooks.com/blog/parallel-session-gitignore-trap-two-destructive-ops/My .gitignore cache was stale, so I read 20 vendored skill files as pollution. Ran git rm --cached, then reverted. Two commits that shouldn't exist.Sat, 09 May 2026 00:00:00 GMTclaude-codeworkflowsgithttps://agentcookbooks.com/blog/six-personas-in-parallel-three-findings-emulated-not-installed/https://agentcookbooks.com/blog/six-personas-in-parallel-three-findings-emulated-not-installed/Six agency-agent personas dispatched as general-purpose subagents — emulated, not installed. Three findings: a frontmatter gap, a schema gap, three a11y gaps.Sat, 09 May 2026 00:00:00 GMTclaude-codeskillsagentshttps://agentcookbooks.com/blog/four-seo-skills-only-sweep-4-found-the-gap/https://agentcookbooks.com/blog/four-seo-skills-only-sweep-4-found-the-gap/Four skills on the same live homepage. Three SEO rubrics returned clean scores. Only copy-editing's Sweep 4 caught the claim-vs-proof colocation gap.Mon, 04 May 2026 00:00:00 GMTclaude-codeskillsseohttps://agentcookbooks.com/blog/skill-security-auditor-not-a-website-tool/https://agentcookbooks.com/blog/skill-security-auditor-not-a-website-tool/A 30-second negative-fit receipt: the skill name reads like website security, but the actual scope is scanning skill code before install. Lesson included.Mon, 04 May 2026 00:00:00 GMTclaude-codeskillsskill-developmentsecurityhttps://agentcookbooks.com/blog/claude-code-cro-content-blog/https://agentcookbooks.com/blog/claude-code-cro-content-blog/Ran /page-cro on a content blog with no signup, no funnel. 4 of 7 framework dimensions applied. The convergence with /copy-editing was the lesson.Sat, 02 May 2026 00:00:00 GMTclaude-codeskillscrohttps://agentcookbooks.com/blog/cloudflare-pages-csp-pagefind/https://agentcookbooks.com/blog/cloudflare-pages-csp-pagefind/The Content-Security-Policy on a static Astro blog with Pagefind search — the two directives nobody documents and what 'unsafe-inline' actually costs you.Sat, 02 May 2026 00:00:00 GMTclaude-codesecuritydeploymenthttps://agentcookbooks.com/blog/claude-code-content-judge-hook/https://agentcookbooks.com/blog/claude-code-content-judge-hook/A PostToolUse hook that sends every content edit to Haiku 4.5 for an editorial-bar verdict. The config, the rubric, and the prompt-caching floor.Thu, 30 Apr 2026 00:00:00 GMTclaude-codehookscookbookhttps://agentcookbooks.com/blog/claude-code-frontmatter-guard-hook/https://agentcookbooks.com/blog/claude-code-frontmatter-guard-hook/A PostToolUse hook validating blog and skill frontmatter against the same zod shape Astro uses at build. Real config, two live blocks captured.Thu, 30 Apr 2026 00:00:00 GMTclaude-codehookscookbookhttps://agentcookbooks.com/blog/cloudflare-ai-audit-robots-txt-trap/https://agentcookbooks.com/blog/cloudflare-ai-audit-robots-txt-trap/Cloudflare's AI Audit feature edge-injects Disallow rules into robots.txt — silently overriding the file you committed. What it blocks, what slips through.Thu, 30 Apr 2026 00:00:00 GMTclaude-codeseohttps://agentcookbooks.com/blog/claude-code-harness-setup-sprint/https://agentcookbooks.com/blog/claude-code-harness-setup-sprint/15 transcripts scanned, 1 permission survivor, 5 misplaced allow rules found, 2 remote agents scheduled: what three harness skills found in 30 minutes.Wed, 29 Apr 2026 00:00:00 GMTclaude-codehooksskill-developmenthttps://agentcookbooks.com/blog/claude-code-skill-activation-hook/https://agentcookbooks.com/blog/claude-code-skill-activation-hook/A PostToolUse hook on the Skill tool: appends a stub to receipts-drafts/. The config, the Node script, and the watcher quirk that took a restart.Wed, 29 Apr 2026 00:00:00 GMTclaude-codehookscookbookhttps://agentcookbooks.com/blog/copy-editing-vs-humanizer/https://agentcookbooks.com/blog/copy-editing-vs-humanizer/Two skills on the same 65-line technical post: copy-editing made 4 edits, humanizer made 0. The negative result and the decision rule it produces.Wed, 29 Apr 2026 00:00:00 GMTclaude-codeskillscopywritinghumanizinghttps://agentcookbooks.com/blog/three-seo-skills-pre-launch-audit/https://agentcookbooks.com/blog/three-seo-skills-pre-launch-audit/Three SEO skills, one pre-launch Astro site, no live URL: title fixed in 3 minutes, full-site scored at 82/100, content E-E-A-T at 65/100.Wed, 29 Apr 2026 00:00:00 GMTclaude-codeskillsseohttps://agentcookbooks.com/blog/claude-code-hooks-cookbook/https://agentcookbooks.com/blog/claude-code-hooks-cookbook/One Claude Code hook, the actual JSON, what it blocks, and the two failure modes I hit. The full cookbook ships after 12 hooks in production.Tue, 28 Apr 2026 00:00:00 GMTclaude-codehookscookbook