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

With no annotations, the description carries the full behavioral burden. It does well on the return surface ('Returns pricing model, price, free tier and auth type') and on matching behavior ('case-insensitive match over title, excerpt and data provided'), which substitutes for the missing output schema. However it says nothing about result ordering, the limit/pagination contract, or whether all matches are returned — meaningful gaps for an unannotated tool.

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, zero filler, correctly front-loaded: purpose first, then match semantics, then return shape. Every clause carries information the agent needs.

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 4-parameter read tool with no annotations and no output schema, the description covers the critical unknowns: what is searched, how matching works, and what fields come back. The remaining gap is the limit/pagination contract and how results are ordered, which leaves it slightly short of fully self-sufficient.

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 50%: query and category are documented, limit and pricing_model are not. The description partially compensates by explaining that the query matches across title, excerpt and data provided (case-insensitively), which is real added meaning beyond the schema's bare example. It adds nothing for limit, and pricing_model is left to a self-explanatory enum.

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?

Uses a specific verb+resource ('Search third-party data APIs ... listed in the directory') and names the matched fields and domain (SEO, analytics, enrichment). It implicitly contrasts with get_api/list_categories through the word 'search', but never names a sibling explicitly, so differentiation is inferred rather than stated.

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 only implied: 'search' suggests exploration when the specific API slug is unknown, versus get_api for a known record. There is no explicit when-to-use/when-not statement, no guidance on empty results, and no pointer to alternatives; only the inline '(see list_categories)' hint for the category parameter.

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