Set port-out PIN

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

Annotations indicate idempotentHint=true, readOnlyHint=false. Description adds extra context: PIN is 'hashed at rest', resets failed-attempt lock, requires MFA. No contradiction. Provides value beyond annotations by explaining security and state implications.

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?

Extremely concise: two sentences plus error list. Critical information is front-loaded. No unnecessary words. Each sentence adds value (action, side effects, requirements, alternatives, errors).

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 mutation tool with no output schema, the description covers the main aspects: input, behavior, errors. It does not describe the return value on success, but given the tool's simplicity and idempotency annotation, this is acceptable. Minor gap.

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% with clear descriptions for both parameters (tn and pin). The description restates the PIN length (4-10 digits) which matches the schema pattern, but does not add new meaning beyond the schema. 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?

The description clearly states the tool's purpose: 'Set the customer-chosen 4-10 digit port-out PIN on a number you own'. It specifies the action (set), resource (port-out PIN), and scope (on owned number). Also notes side effects (resets lock) and distinguishes from sibling tools num_get_port_out_pin and num_remove_port_out_pin.

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?

Provides explicit guidance: when to use (set PIN), prerequisites (step-up MFA), related tools for alternative actions (check current state, clear), and enumerates possible errors (INVALID_REQUEST, INVALID_PIN, TN_NOT_OWNED). No ambiguity.

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