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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the description doesn't need to restate safety. It adds context about the return value (null on invalid slug) and the scope of information retrieved (full description, launch date, revenue signals, for-sale status), which are beyond the schema. It doesn't discuss permissions or rate limits, but for a read-only fetch with good annotations, this is adequate.

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 with zero waste. The first sentence communicates purpose and input format; the second gives usage context and return behavior. Information is front-loaded with the most important details first.

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 the tool has one parameter, a clear input format, an output schema, and strong annotations, the description covers essential aspects. It explains when to use, what it returns (including null case), and the slug format. It doesn't detail the output structure since the output schema exists, and it doesn't mention any edge cases beyond null, but for a simple retrieval tool it's complete enough.

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% with a single parameter 'slug', and its description ('The tool's listing slug.') is minimal. The tool description adds crucial semantics by showing the exact format ('/tools/acme-writer' -> slug 'acme-writer') and clarifying it's the same slug returned by search_tools' toolUrl, which the schema alone doesn't convey. This exceeds baseline.

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 fetches full public detail for one AI tool by slug, specifying the exact input format (e.g., '/tools/acme-writer' -> slug 'acme-writer') and its relationship to search_tools. It distinguishes itself from siblings like search_tools (which lists) and list_alternatives/list_offers (which retrieve other entities), making the purpose unambiguous.

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 explicitly says 'Call this after search_tools' and elaborates that it retrieves a tool's full description, launch date, revenue signals, and for-sale status. It also mentions the failure mode ('Returns null if the slug doesn't resolve'), giving clear guidance on when to use it and what to expect.

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