Update number metadata

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

Annotations indicate it's a non-read, non-destructive, idempotent mutation. The description adds context about what can be updated (friendly name and description) and lists possible errors (INVALID_REQUEST, TN_NOT_OWNED), which goes beyond 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 sentences plus error list, zero waste. Front-loaded with the core action ('Update...'). Every sentence adds value.

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 three required/optional string parameters and no output schema, the description covers purpose, usage, alternatives, and errors. It is fully adequate.

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 all three parameters described in the input schema. The description only mentions 'friendly name and/or description', adding minimal meaning beyond the schema's descriptions.

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 'Update the friendly name and/or description on a number you own,' providing a specific verb and resource. It distinguishes from siblings by mentioning alternative tools for routing/E911/CNAM and messaging.

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 states when to use this tool ('to label numbers for humans') and when to use alternatives ('for routing/E911/CNAM use num_update_voice, for messaging use num_update_sms'), providing clear context and exclusions.

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