sync_sms_twilio_number

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

Annotations already declare readOnly=false, openWorld=true, idempotent=false, destructive=false, so the mutation profile is carried by structured data. The description adds the target endpoint path but does not say what happens when the number is already assigned elsewhere, or what a repeat sync does despite being non-idempotent.

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?

Three short sentences, front-loaded with the core action, followed by the channel exclusion and body guidance. The API-path reference is slightly jargon-heavy but earns its place by mapping to the payload contract.

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 single nested-object mutation with no output schema, the description covers what the tool does, what to put in the payload, and which channel it applies to. Missing only edge-case behavior such as reassignment conflicts, which keeps it from a 5.

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?

With one nested opaque object parameter at 100% schema coverage, the schema only says 'Full request body object'. The description compensates by naming the expected body fields (phoneNumber or sid, plus agentId), which is genuine meaning beyond the schema.

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?

States a specific verb and resource: 'Assign a Twilio number to an agent for SMS handling'. The SMS-vs-WhatsApp scoping distinguishes it from WhatsApp number handling, but it does not clarify its relationship to the closely named siblings import_twilio_number, release_twilio_number, or check_twilio_number.

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 excludes WhatsApp routing and points to the alternate path (waNumbers/{phoneId}, origin 'whatsapp'), which is useful channel-level guidance. However, it never says when to use this instead of import_twilio_number or release_twilio_number, which is the more likely point of confusion for an agent.

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