register_sender_id

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

No annotations are provided, and the description only repeats the basic action. It does not disclose side effects, what happens upon duplication, whether approval is needed, or any constraints beyond the character limit. The description fails to compensate for the lack of 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 a single sentence, which is concise. However, it omits crucial details such as behavior, return value, or usage context, making it under-specified rather than efficiently informative.

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 lack of annotations and the existence of an output schema (not described), the description is incomplete. It does not mention what the tool returns, potential errors, or any post-registration effects. For a registration action, this is insufficient.

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?

The input schema has no description coverage (0%). The tool description adds the character limit for `sender_id` but does not explain the `purpose` parameter's expected values or format. Since schema coverage is low, the description should elaborate more, but it only partially addresses one parameter.

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 action 'register a sender ID', specifies the character limit (≤ 11 chars), and mentions the required parameter `purpose`. This distinguishes it from sibling tools like `check_sender_id` which checks status rather than registering.

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?

No guidance is provided on when to use this tool versus alternatives (e.g., `check_sender_id`). There is no mention of prerequisites, required permissions, or situations where registration is not appropriate.

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