Send a text message

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 mutation profile is covered. The description still adds real value beyond that: delivery is asynchronous ('queued and sent at the account's pace') and the result carries 'id' and 'queued' status, which is the key operational trait for a fire-and-forget send. It stops short of stating auth requirements or rate limits.

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 purpose, then delivery semantics and return fields, then the consent caveat. No filler, and each sentence carries information the agent needs.

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?

With six parameters, three required, no enum values and no output schema, the description compensates by describing the return fields (id, queued) and the async delivery model, which the schema does not cover. Parameter-level detail is delegated to a fully described schema, so the only remaining gap is permission/account prerequisites.

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%, so the schema already explains to, text, mentions, accountId, idempotencyKey and replyToMessageId in detail. The description adds nothing about any individual parameter, so the baseline 3 applies.

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 names a specific verb and resource ('Send a text message') plus the destination scope ('from a linked number to a contact, group or channel'), which cleanly separates it from siblings like send_media, send_location, send_poll, and reply_to_message. An agent can pick this tool without opening the 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?

It implies the context (linked number, contact/group/channel recipient) and adds a consent caveat ('Send only to people who expect it'), but it never names alternatives such as reply_to_message, send_media, or send_poll, nor states when this tool is the wrong choice. Usage is inferable but not explicitly routed.

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