import_twilio_number

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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true, idempotentHint=false), and the description adds genuinely new context: the operation consumes the caller's Twilio account credentials and proxies a specific backend endpoint. It stops short of saying what happens if the number is already imported elsewhere or whether validation occurs first.

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 sentences, each earning its place: purpose first, exclusion second, payload guidance third. No repetition of the tool name and no filler.

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 opaque payload wrapper with no output schema, the definition tells an agent what the call does, what credentials are needed, and what to put in the body. Missing only edge-case behavior (duplicate number handling, return value), which is a modest gap rather than a blocker.

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%, but the schema description is only a generic pointer ('Full request body object for /utils/import-twilio-number'), so the description carries the real semantic load by enumerating typical payload contents (account SID, auth token, phone number, optional agentId and capabilities). It does not mark which fields beyond payload are strictly required or give field formats.

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 ('Import a Twilio SMS/voice number') plus scope ('you already own into the workspace'), and explicitly contrasts itself with the WhatsApp/Meta path named via waNumbers. An agent can distinguish this from siblings like sms_numbers_write or whatsapp_numbers_write without opening any schema.

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?

Gives an explicit exclusion ('This is NOT a WhatsApp Cloud API connection; do not use it for waNumbers/Meta WhatsApp') and states the precondition (you must own the number and supply Twilio credentials). It does not name the specific sibling to use for WhatsApp numbers or point at check_twilio_number/sync_sms_twilio_number as related steps, so routing is clear but not fully closed.

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