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

With readOnlyHint=true already covering the safety profile, the description adds genuinely non-structured information: the operation consumes 1 credit, and the search runs against a pre-built index rather than live data. It stops short of describing result format or ordering, but the cost disclosure is the important behavioral fact here.

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 short sentences, front-loaded with what the tool does and the corpus it hits. Nothing is redundant and no sentence is filler.

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 3-parameter tool with 33% schema coverage and no output schema, the description leaves important gaps: what a result contains (post text? metrics? similarity score?), how to interpret ranking, and what the platform filter constrains. An agent could call it, but not predict or use the output well.

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 only 33% — only 'text' is documented, and even that merely echoes the description's 'post idea'. Neither 'limit' (capped at 20) nor 'platform' is explained anywhere, so the description should have compensated for the uncovered parameters and does not.

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?

Names a specific operation (similarity search) and a specific corpus (already-indexed viral posts), which is more precise than the bare title. However it does not distinguish itself from close siblings like similar_content or search_viral_content, so an agent could not tell from the description alone which one to reach for.

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?

"Useful to validate a post idea" gives one concrete triggering scenario, which is real usage guidance. But there is no when-not guidance, no mention of the near-duplicate siblings, and no prerequisites (e.g. whether the index must be populated first).

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