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

Beyond the annotations, it discloses the key caveat that a clean result is not a guarantee of safety and that only pattern matches are reported, and it documents error behavior in detail (never raises a protocol error, returns an error object with remediation). The read-only/idempotent restatement is redundant with the annotations but the remaining content is substantive and non-obvious.

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?

Purpose and scope are front-loaded in the first sentence, followed by usage, an inline example, exclusions, and error contract. Dense but nearly every clause earns its place; the 'FREE.' token and the inline return-shape block are slightly less essential, especially since an output schema exists.

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?

Covers purpose, exclusions, caveats, error handling, and retry safety, which is more than enough for a one-parameter tool. The inline description of the return object duplicates the existing output schema, so it is redundant rather than missing, but nothing an agent needs to call it correctly is absent.

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 coverage is 100% and the single parameter is already documented, so the baseline is 3. The description adds a concrete call example ({'text': '<untrusted content>'}) that clarifies the expected packaging of the input as a single pasted string, which is marginal but real added value.

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 and resource (scan untrusted text for prompt-injection patterns) plus the timing constraint (before ingestion). It explicitly names the sibling it is not (audit_skill_file) and scopes itself to web pages, emails, and documents, so an agent can separate it from audit tools without opening a schema.

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?

Gives a clear when-to-use ('on any web page, email, or document an agent is about to ingest') and an explicit when-not ('not for reviewing a skill file you control — use audit_skill_file'). The alternative and the condition that selects it are both named.

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