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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=true, so the safety profile is covered. The description adds valuable behavioral context: URLs are signed with an expires_at, rooms usually end before signatures expire, and FLV is always available while HLS is conditional. This explains failure modes and fallback behavior beyond what annotations 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?

Three sentences with zero waste. The core purpose is front-loaded, followed by the most important behavioral caveat (signed URLs, room lifetime) and a practical fallback tip. Every sentence earns its place.

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 read-only list tool with 100% schema coverage and no output schema, the description covers the key operational details: what you get (stream URLs per quality, title, viewer count), the caveats (signed URLs, room lifetime), and the fallback strategy. The only minor gap is not describing the compact response structure, but the expand parameter's schema description covers that.

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 schema already documents all three parameters (q, count, expand). The description adds context about the expand parameter's purpose (compact vs. complete response) and the practical implication of large responses, but this is already partially in the schema. The description doesn't add much beyond what the schema provides, so baseline 3 is appropriate.

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: 'Live rooms matching a keyword' with playable stream URLs, title, and viewer count. It clearly distinguishes itself from sibling tools like tiktok_search_lives by focusing on playable stream URLs and quality formats, not just search results.

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 gives clear context on when to use this tool: when you need playable stream URLs for live rooms matching a keyword. It doesn't explicitly name alternatives or exclusions, but the focus on stream URLs and quality formats implies when it's appropriate versus other search tools. The guidance about trying another quality if one fails is practical usage advice.

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