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

Annotations already declare readOnlyHint=false, destructiveHint=true, and idempotentHint=false; the description adds two things annotations cannot convey: PATCH-style merge semantics (omitted fields persist) and the required `channels:write` scope. It does not expand on the destructive surface (e.g. that mutating `key` breaks integrations), which the schema carries instead.

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 the action and immediately followed by the merge rule and the permission requirement. The only inefficiency is the redundant restatement of 'Update a channel' in the title line and the first sentence.

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 destructive, non-idempotent mutation over a nested object with ~18 settable fields and no output schema, the description covers the permission gate and partial-update behavior but says nothing about what the call returns, whether nulling fields is possible, or the risk that changing certain fields breaks downstream integrations. Adequate, not complete.

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?

Top-level schema description coverage is reported as 0% for the single `request` parameter, so the description is expected to compensate. It only partially does: the merge semantics explain how the nested `body` behaves, but nothing describes the request envelope or which field groups exist. Individual body properties are documented inside the schema itself.

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 and resource ('Update a channel'), which cleanly separates it from siblings like channels-create, channels-delete, channels-retrieve, and channels-duplicate. It stops short of explicitly naming any sibling or noting what makes update distinct beyond the verb.

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?

'Fields you leave out keep their value' is a genuine usage rule that tells the agent to send partial bodies rather than a full object, and the permission line signals a precondition. But there is no guidance on when to use this versus channels-create/channels-duplicate, nor any exclusion or ordering advice.

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