Update voice configuration

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

Annotations indicate idempotentHint=true, readOnlyHint=false, destructiveHint=false, which are consistent with the description's update semantics. The description adds error types (INVALID_REQUEST, TN_NOT_OWNED) but does not detail other behavioral aspects like provisioning time or synchronicity. Overall adds value without contradicting 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?

The description is three sentences: main action, usage guidance, and alternatives. It is front-loaded and efficient. The error list is appended concisely. Could be slightly more integrated, but overall well-structured.

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?

Given the tool's complexity (9 params, state-changing), the description covers prerequisites (owning the number), alternatives, and common errors. No output schema exists, but the description does not need to detail return values. It provides sufficient context for selecting and invoking the tool correctly.

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% for 9 parameters, so the schema already explains each parameter. The description only summarizes the categories (routing, E911, CNAM) without adding new parameter details. Baseline score of 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 or update the voice routing, E911, and CNAM configuration on a number you own.' It distinguishes from sibling tools by specifying when to use num_delete_voice_config and num_bulk_route instead. The mention of errors adds specificity.

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?

Explicit usage guidance: 'Use after ordering a number (num_order) to bring it into voice service, or to change routing later.' It also tells when not to use it (disable voice: use num_delete_voice_config; bulk route: use num_bulk_route). This clarifies the appropriate context.

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