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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the read-only nature is structurally known. The description adds meaningful behavioral context by specifying the response contents (full profile including a few recent client reviews) and by explaining that the slug is derived from the profile URL. It does not describe error/not-found behavior, but that is minor for a simple read operation.

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-loaded: the core purpose appears first, followed by the return payload and usage guidance. Every sentence earns its place, and there is no repetition of the schema or annotations.

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?

For a single-parameter read-only tool with full schema coverage and rich annotations, this description is complete. It tells the agent what the tool does, when to use it, how to get the slug, and what data will be returned. The lack of an output schema is compensated by the explicit field list in the description.

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?

The schema covers the single parameter well (100% coverage, field name, example), so the baseline is 3. The description adds real value by defining the slug as 'the last path segment of its profile URL' and by warning agents not to guess it, which is essential for correct invocation.

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 states a specific verb ('Fetch'), a specific resource ('a single agency's full profile'), and identifies the key identifier ('slug'). It also enumerates the returned fields (description, location, rating, services, website, reviews), and clearly distinguishes itself from the sibling list/search tools by focusing on fetching details for one known agency.

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 description provides explicit WHEN TO USE guidance: after search_agencies or match_agencies returns a relevant result, or when the user names a specific agency with a known slug. It also gives an explicit exclusion: 'Don't guess slugs - find them via search_agencies first.' This fully routes the agent to the correct workflow.

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