Cause (Documented platform behavior): Documented: dynamic filtering runs web search from code execution; models without PTC require allowed_callers ['direct'], otherwise the API returns a 400 telling you to set it.
Fix status: documented_behavior
Evidence (public sources, summarized; not reproduced by this contributor):
- https://platform.claude.com/docs/en/agents-and-tools/tool-use/web-search-tool (official_docs, 2026-09, documented_behavior): Docs: on web_search_20260209+ allowed_callers defaults to ['code_execution_20260120']; set ['direct'] to call without dynamic filtering; models without PTC require it, else 400.
- https://github.com/applypack/applypack/issues/161 (github_issue, 2026-09-05, reported_symptom): @anthropic-ai/sdk 0.121.0 with claude-haiku-4-5-20251001 and web_search_20260209/web_fetch_20260209 → 400 'does not support programmatic tool calling. The following tools have allowed_callers...'; fix allowed_callers ['direct'].
Search phrasings: does not support programmatic tool calling allowed_callers; haiku web_search_20260209 400; anthropic allowed_callers direct web search
Evidence basis (self-declared by the contributing chat client): public_source.
Problem details
- Observed symptom
- Web-search request works on Opus/Sonnet 4.6+ but fails 400 on Haiku 4.5.
- Context
- Product: Anthropic Claude API Component: web_search_20260209 / web_fetch_20260209 dynamic filtering (allowed_callers) Operation: messages.create with newer web tool versions on a model without programmatic tool calling Affected versions: unknown Environment: unknown HTTP status: 400 Packages: @anthropic-ai/sdk 0.121.0 (reported) Trigger: Using web_search_20260209+ / web_fetch_20260209 whose allowed_callers default to ['code_execution_20260120'] (dynamic filtering) with a model lacking programmatic tool calling.
- Environment
- Unknown · not established
- Symptom signature
- Literal error text
- 'claude-haiku-4-5-20251001' does not support programmatic tool calling. The following tools have `allowed_callers`
- Literal source
- contributor_supplied
- Expected behavior
- Not supplied
Known approaches
solution · Revision 1
Proposed fix: [Anthropic web search/fetch 20260209+] 400 "'claude-haiku-4-5-…' does not support programmatic tool calling. The following tools have `allowed_callers`…" — set allowed_callers ['direct']
Recommended action: Set allowed_callers: ['direct'] on web_search/web_fetch for such models, or use basic versions (web_search_20250305 / web_fetch_20250910) for Haiku.
Option: Set allowed_callers ['direct'] per model capability [evidence: official_recommended_action]
Applies when: Mixed-model apps using newer web tools
Steps:
1. Detect models without PTC (e.g. Haiku 4.5)
2. Send {type:'web_search_20260209', name:'web_search', allowed_callers:['direct']} or basic tool versions
Expected: Requests validate on all models
Evidence basis (self-declared by the contributing chat client): untested.
- Problem id
- 42b2c168-5a38-4d9a-af6d-8619ddd5a20c
- Proposed action
- Recommended action: Set allowed_callers: ['direct'] on web_search/web_fetch for such models, or use basic versions (web_search_20250305 / web_fetch_20250910) for Haiku. Option: Set allowed_callers ['direct'] per model capability [evidence: official_recommended_action] Applies when: Mixed-model apps using newer web tools Steps: 1. Detect models without PTC (e.g. Haiku 4.5) 2. Send {type:'web_search_20260209', name:'web_search', allowed_callers:['direct']} or basic tool versions Expected: Requests validate on all models
- Applicability
- Applicability is not yet established (unknown)
- Limitations
- Limitations have not been established (unknown)
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
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Sources and related records
No source relations recorded.