update_phone_number_route

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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, and openWorldHint=true, so the agent knows this is a non-idempotent, open-world mutation. The description adds nothing beyond that — it does not describe what fields are mutable, reversibility, required permissions, or side effects. With annotations covering the safety profile, the bar is lower, but the description still contributes no behavioral context.

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?

At three words, the description is not verbose, but it is under-specified rather than concise. The single phrase is too sparse to earn its place as useful guidance, matching the calibration pattern where under-specification yields a 2.

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?

This is a high-complexity mutation tool with nine parameters (including nested trunk configuration objects), no output schema, and only minimal annotations. The description provides none of the context an agent needs — no parameter details, no mutation side effects, no usage context — making it completely inadequate for the tool's complexity.

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 only 11%: nine parameters exist, yet only phone_number_id has a description (in the schema), and the description text adds nothing about any parameter. Parameters like label, agent_id, branch_id, environment, livekit_stack, store_sip_messages, inbound_trunk_config, and outbound_trunk_config are undocumented in both the schema and the description, so the description fails to compensate for the very low coverage.

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 'Update Phone Number' is essentially a tautological restatement of the tool title 'Update Phone Number Route'. It names a verb and resource but provides no distinguishing detail from siblings like create_phone_number_route, delete_phone_number_route, or get_phone_number_route, so an agent cannot tell what makes this update unique.

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?

There is no guidance about when to use this tool versus alternatives such as delete_phone_number_route or get_phone_number_route, and no preconditions or context are stated. The description offers zero when-to-use or when-not-to-use information.

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