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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false), so the description's added value is the return contract: slug, category, cancellation method, and guide URL. That is the useful extra context. It doesn't mention pagination, empty results, or ranking behavior, keeping it below 5.

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?

Three tight sentences: purpose and scope first, return fields second, next-step routing last. No filler and no repetition of the schema.

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 fills that gap by enumerating the returned fields, and it closes the loop with the follow-up tool. For a two-parameter read-only search, nothing an agent needs before calling is 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?

Schema coverage is 100%, so both parameters are already documented, including partial-name matching and the 1–10 limit. The description adds value by showing that brand-style names ('planet fitness') and service names ('netflix') both work, clarifying what to put in the query field beyond the schema's generic phrasing.

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 ('Find companies by name') plus the scope ('among the subscriptions and memberships Postbye has a cancellation guide for'), and names the sibling that consumes the output ('Use the slug with get_cancellation_guide'). Despite a title that says 'Search cancellation guides', the description makes clear the object being searched is companies, which an agent can distinguish from get_cancellation_guide and list_categories.

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 clearly implied and partly explicit: search by company name, then pass the returned slug to get_cancellation_guide. Concrete example queries ('netflix', 'planet fitness') anchor when this tool applies. It lacks an explicit when-not statement (e.g., what to do when there is no guide for a company), so it stops short of a 5.

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