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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds real behavioral context: it reads the connected channel directly, needs no input, and should be invoked without asking the creator anything. It also previews what the diagnosis returns (view source, arrival door, actual searches, one change to make).

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?

Purpose is front-loaded, but the body is a single dense block that exhaustively lists near-duplicate user phrasings ('why am I not getting discovered or found, how do I get found or rank...' etc.). The routing value is real, yet the enumeration is longer than it needs to be and the trailing imperative adds bulk.

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 carries the return-value burden and does so by naming the diagnosis dimensions. For a zero-required-param read tool it is nearly complete; the undocumented `title` parameter is the only unresolved gap.

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%, with `video` documented in both schema and description (title/fragment/'latest', omit for whole channel, reach-vs-conversion framing). The description enriches `video` with the reach-vs-conversion purpose and the 'specific video' trigger, but the `title` parameter remains undocumented in either place.

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 (Diagnose how...gets FOUND) and a scoped resource (the signed-in user's own channel), and explicitly distinguishes itself from analyze_audience, analyze_video, and diagnose_channel. An agent can identify the tool's job without opening the schema.

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?

Names alternatives and the exact condition that selects each ('For WHO the audience is... use analyze_audience; for a single video's overall performance... use analyze_video; for the ranked list... use diagnose_channel'). It also enumerates the user phrasings that should route here, leaving little to inference.

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