Release a phone number

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

Goes well beyond the destructiveHint=true / idempotentHint=false annotations: it discloses that a release_fee is charged, that the number stops serving calls immediately, that the default state is a recoverable 24-hour cooldown with a refund path, and that after the window the number may not be recoverable. The irreversibility of immediate:true and the env-var gate are exactly the side effects an agent must know before invoking a destructive tool.

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 tightly packed sentences with the resource and endpoint front-loaded, followed by cost, state transition, reversal window, and gating. Every clause carries decision-relevant information; nothing is 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, no-output-schema tool, the description covers cost, state transitions, reversibility window, the cancel alternative, and the two preconditions. It even names the release_fee field returned, so nothing an agent needs in order to call this safely 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 67% — confirm and immediate are documented in the schema, but phone_number is only constrained by a pattern. The description compensates by explaining the semantic distinction between the two modes (default cooldown vs. non-cancellable immediate) and why confirm is required. It does not add format/syntax detail for phone_number beyond the pattern, so it falls short of a 5.

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 precise verb and resource ('Release a phone number from this Vobiz account') plus the underlying endpoint DELETE /numbers/{e164}. This clearly separates it from siblings like cancel_number_release, buy_phone_number, and update_phone_number without needing to open any 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?

Explicitly describes the default path (pending_release with a 24-hour cooldown) and names the alternative that reverses it ('cancel_number_release restores it and refunds the fee'), plus the condition that selects the other mode ('immediate: true skips the cooldown and cannot be cancelled'). It also states the two gates (VOBIZ_ENABLE_PROVISIONING and confirm: true) so an agent knows the call will fail without them.

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