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

The readOnlyHint annotation already signals safety, and the description adds useful behavioral requirements: preserve returned fields, respond in the visitor's language, cite source_url, and avoid inventing facts. These go beyond the annotation and help the agent interact correctly.

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 front-loaded with the core purpose and then gives concise usage and response instructions. It is slightly dense with multiple directives, but every sentence adds practical guidance and none are redundant.

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 no output schema, the description helpfully names the expected returned fields: id, title, qualifiers, dates, and source_url. It also covers language and citation behavior. It does not detail edge cases like multiple results, but the coverage is sufficient for a simple read-only lookup.

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%, so parameter basics are already documented. The description adds meaningful semantic distinction: slug targets one known page, while query performs a bounded keyword search. This clarifies how to choose between the two optional parameters.

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 the tool's action: 'find or read a public face-shape guide.' It also differentiates two access modes—slug for a known page and query for a keyword search—so an agent understands what the tool does and how to target it.

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?

There are no sibling tools to distinguish from, but the description gives clear context: use this read-only tool for public face-shape guides. It explicitly instructs when to use slug versus query, which is practical usage guidance even though it does not list exclusions or alternatives.

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