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

With no annotations provided, the description carries the full burden and does so thoroughly. It discloses that the operation is read-only, requires no authentication, returns up to 10 matches with detailed fields, ranks by uptime and endpoint count, and explicitly states it does not call any upstream API or debit credits. This exceeds what annotations would typically provide.

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 appropriately sized at about five sentences, each earning its place: read-only status, purpose, return format, auth requirement, usage guidance, and side-effect disclosure. It is front-loaded with the most critical info and contains no filler or redundancy.

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?

The description is complete for a search tool with no output schema. It covers purpose, filters, result count and ranking, return fields, auth, alternatives, and side effects (no upstream call/no credits). The absence of an output schema is compensated by explicitly listing the fields included in each match, making the tool fully self-contained.

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 description coverage is 100%, so the baseline is 3 per guidelines. The description adds minimal extra meaning beyond the schema—it mentions 'free-text query' and 'optional category, price, and type filters' but does not provide new syntax or semantics. The schema already fully documents each parameter, including valid values and units, so the description adds marginal value.

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 uses a specific verb ('Searches') and resource ('onboarded APIHub services'), clearly distinguishing it from siblings. It explicitly names alternatives (apihub_list_services, apihub_search_external, apihub_get_service) and states the scope of the search, making the tool's 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 provides explicit when-to-use guidance: 'Use this when you need to find an API by capability' and then lists alternatives with their specific use cases (browse without a query, include external catalog, already know a slug). This directly tells the agent when to choose this tool over siblings.

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