Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered elsewhere. The description adds that the operation is a whole-array, one-call transformation and gives the endpoint path, but it never says what the call returns, whether the original messages are modified, or what the sanitizer does when it flags injection, leaving a real gap for a security tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, front-loaded with the core action and scope, with no padding. Minor cost: the 'Policy Proxy & Sanitizer API' phrasing and the parenthetical endpoint repeat the title/annotations rather than adding new operational meaning.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With six parameters, no output schema, and a security-sensitive transformation, the description should at least sketch the response shape (sanitized messages plus findings) and the effect of the sensitivity/redaction flags. It covers the what and where adequately but leaves an agent unable to predict results before calling.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the structured fields already document all six parameters, and the baseline of 3 applies. The description contributes only the meaning of 'messages' as a multi-turn array; the behavior flags (redact_pii, scan_secrets, strip_email_quotes, check_prompt_injection) and 'sensitivity' values are never explained or given an example.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (sanitize) and resource (entire multi-turn LLM messages[] arrays) and clarifies the operating scope ('in one call') plus the downstream providers. This distinguishes it reasonably well from siblings like tinplate_prompt_guard and tinplate_llm_output_guard, though it never names an alternative explicitly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The phrase 'before forwarding to OpenAI, Anthropic, or Gemini' gives useful timing/context for when to call it, which is more than most tools offer. However, there is no guidance on when NOT to use it, no named alternative for single-prompt or output-side sanitization, and no prerequisites stated.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.