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

Annotations already declare readOnlyHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds real value beyond that: the exact result payload (post text, author, engagement metrics, media, link previews, permalinks) and a concrete billing rate of $0.006 per request. It omits auth, rate limits and pagination, keeping it from a 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 short sentences, front-loaded with purpose, then payload, then cost. No filler or repetition. The engagement-metrics parenthetical is dense but informative, and the price note is appropriately placed last.

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 correctly takes on the burden of describing return fields, and it does so thoroughly. For a simple two-parameter search tool with full schema coverage and safety annotations, the only meaningful gap is pagination/result-limit behavior and how it relates to the sibling thread tools.

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 both the query length limit and the get_sentiment surcharge are already documented in the schema. The description body adds no parameter-level detail of its own, which matches the baseline 3 for full schema coverage.

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 states a specific verb and resource ('Search Threads (Meta) posts by keyword'), clearly separating a post search from a user search such as search_threads_users. It also names the platform to disambiguate from search_twitter/search_bluesky. It stops short of explicitly routing the agent away from any sibling, so it sits at a strong 4 rather than a 5.

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?

There is no when-to-use or when-not-to-use guidance, and no alternatives are named. The agent gets no help deciding between this, search_threads_users, threads_user_posts, or the other platform search tools. Usage is only inferable from the tool name.

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