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

With annotations already declaring readOnlyHint=true and openWorldHint=false, the description adds substantial behavioral context: it is rule-based, makes no model call, never echoes flagged text, reports findings per line, returns a structured result shape, and charges 1 credit per successful call with schema-invalid input rejected before billing. These details go well beyond the annotations.

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?

The description is compact and front-loads the main behavior: what it flags, how it runs, privacy, return shape, and billing. It is dense but not wasteful, though the single long sentence structure makes it slightly harder to scan than shorter separated clauses.

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?

Given a single required parameter, complete schema coverage, read-only annotations, no output schema, and no open-world concerns, the description supplies the missing return-value structure, privacy behavior, billing model, and rejection semantics. Nothing critical for correct invocation appears to be missing.

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?

There is only one parameter, and schema description coverage is 100%, so the schema already documents the prompt input and its 60,000-character limit. The description does not add meaningful parameter-level constraints beyond what is already in the schema.

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?

The description clearly states a specific verb and resource: it flags prompt-injection phrasing, chat-template tokens, hidden characters, PII and secrets, and lists {{variables}}. This is specific enough for an agent to understand what the tool does, but it does not explicitly differentiate itself from sibling tools such as prompt-inject-scan or pii-redact.

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?

Usage is implied — the tool is for checking prompt or template text for safety issues — but the description gives no explicit when-to-use guidance, no when-not-to-use conditions, and no named alternatives for overlapping sibling tools. It provides billing and schema-rejection context, which helps an agent call it, but not selection guidance.

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