Preview what a hangup would drop

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

Annotations already declare readOnlyHint=true, so the non-mutating nature is partly redundant, but the description adds real value: it explains the matching behavior (exact match plus near misses) and the read-only-mode availability, which annotations do not convey. It stops short of describing output shape or limits on the near-miss list.

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 core action, then the blast-radius rationale, then the availability caveat. No filler and nothing buried mid-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 single-parameter read-only preview with no output schema, the description covers what it does, what it returns at a high level (exact match plus near misses), and its availability constraints. Nothing an agent needs in order to call it correctly is missing.

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 baseline is 3, but the description adds matching-resolution semantics — that the single channel argument yields an exact match plus near misses — which the schema does not state. It also pins the argument as identical to asterisk_hangup's, which helps an agent reuse a known value.

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: 'Show which live channels a hangup would affect, without touching them.' The preview-vs-execute distinction from the sibling asterisk_hangup is explicit, so an agent can pick between them without inspecting 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?

Explicitly routes usage: 'see the blast radius before dropping a call,' and names asterisk_hangup as the tool it mirrors ('takes the same channel argument as'). It also states the precondition-free case ('Always available, including in read-only mode'), leaving little to infer.

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