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

Annotations already declare a safe read (readOnly, idempotent, non-destructive, closed-world), and the description adds value beyond them: per-row billing with `limit` capping both rows and cost, the exact returned columns, and a prompt-injection warning that results are untrusted user-generated content. That is behavioral context an agent cannot get from the structured fields.

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?

Four compact sentences, front-loaded with what the tool does and what to use instead; the billing and trust caveats follow. Every sentence carries distinct information with no repetition of the name or title.

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 compensates by enumerating returned fields, disclosing the billing model, and flagging untrusted content. An agent has everything needed to call this correctly and interpret the results.

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 the baseline is 3. The description goes slightly beyond the schema by explaining matching semantics ('case-insensitive substring match') and the cost implication of `limit` ('caps both rows and cost'), which the schema's 'Max rows to return' does not convey.

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 (search) plus resource (TikTok video descriptions) with the matching semantics (case-insensitive substring) and sort order (most-liked first). It also names the sibling tools it is not: `search_tt_hashtags` and `search_tt_comments`, so an agent can route without opening schemas.

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?

Explicit when-to-use ('find videos about a topic or brand') and explicit alternatives with the condition that selects each ('use search_tt_hashtags for hashtags and search_tt_comments for comments'). Nothing is left to inference.

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