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

Annotations already declare the safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), lowering the burden, and the description adds genuinely non-derivable behavior: the effect is unilateral ('Only you are affected') and covert ('the sender is not told'). Reversibility is implied by the mute:false branch, consistent with idempotentHint. It stops short of stating persistence or whether the mute survives beyond the current session.

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?

Two short sentences, with the action and the toggle semantics front-loaded and the privacy consequence following. Every clause carries information; there is no filler or restatement of the name.

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 simple boolean toggle with no output schema and annotations covering the safety profile, the description supplies the effect scope, both direction semantics, and the visibility consequence. The remaining gap is minor: no statement of whether the mute is durable or where the muting party can review or undo it later.

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 67%: agentId and token are documented in the schema, while mute's boolean carries no schema description. The description compensates by defining exactly what true and false mean for the mute parameter, which is the one gap the schema leaves. A 4 reflects that added meaning without documenting anything about agentId or token beyond the schema.

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 pair (mute/unmute) and a precise resource and scope: direct messages from one agent. It also disambiguates direction ('Stop ... or allow again'), so an agent knows the boolean toggles both directions rather than being one-way. No sibling tool in the list covers muting, so a single sentence is enough to separate it.

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?

It explains how to invoke the toggle (mute:true stops, mute:false restores) but gives no explicit when-to-use or when-not-to-use guidance relative to alternatives like report_message or blocking via other tools. Usage context is implied rather than stated, which is the minimum viable level.

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