releasePhoneNumber

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

Annotations already flag destructiveHint=true, readOnlyHint=false, and openWorldHint=true. The description adds useful behavioral context beyond those flags: releasing the number stops rental charges at the next renewal and is only valid for numbers currently allocated to the account. It does not contradict 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?

Two tightly written sentences state the action, the consequence, and the precondition with no filler. The tag line is the only extra, and it does not degrade readability.

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 one-parameter destructive action with destructiveHint already present, the description provides the necessary context: what happens (stop rental), the cost effect (no renewal charge), and the valid condition (allocated number). No output schema is present, and none is needed for this simple release operation.

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?

The schema already documents phone_number with 100% coverage, so the baseline is 3. The description adds a meaningful selection constraint on that parameter: only numbers currently allocated to the account are valid inputs. It does not provide format details, but those are not demanded by the schema's simple string type.

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 uses a specific action ('Give up a phone number and stop its rental') and clarifies the financial consequence, so an agent immediately knows this is the tool for ending a phone number's rental. The precondition 'Only a number currently allocated to the account can be released' distinguishes it from number acquisition/import/detach operations among the siblings.

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?

The description implies the tool is appropriate when a number is currently allocated and should no longer be rented, but it does not explicitly name alternatives (e.g., detachPhoneNumber) or state when not to use this tool. The guidance is contextual but left to inference.

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