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

Annotations already declare destructiveHint=true and idempotentHint=false, but the description goes further: it warns the action cannot be undone, discloses the cascade behavior for group trunks, and states the DID-routing blocker that will cause failure. These are behavioral traits the agent cannot derive from the annotations.

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?

Four tight sentences ordered by importance: what it does, that it is irreversible, what blocks it and how to unblock, then the cascade caveat and return value. No filler.

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 tool with no output schema, the description covers safety, preconditions, alternatives, cascade semantics, and the success response. 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 description coverage is 100% and the schema already documents both id and the two-step confirmation_token flow. The description's restatement of the uuid source adds little beyond the schema, so the 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?

States a specific verb (delete) and resource (SMS trunk), scoped to the authenticated customer and identified by the uuid from list_sms_trunks. It also distinguishes itself from the nearby delete_trunk and delete_sms_trunk_group siblings by explaining that deleting a GROUP trunk cascades to member trunks.

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?

Gives an explicit precondition (a trunk with DIDs still routing SMS cannot be deleted) and names the remedy with the exact alternative call: assign_did_to_sms_trunk with a null sms_trunk_id, or rerouting to another trunk. This is when-to-use and when-not-to-use guidance with the alternative named.

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