get_user_status

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

Describes that it queries Signal servers, returns status, and accepts batches. Discloses limitation about privacy-mode. Without annotations, the description carries the full burden and does so effectively, though it could explicitly state that it's read-only.

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?

Concise, with 4 sentences. The main purpose is front-loaded, and each sentence adds value without redundancy.

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 simple tool with one parameter and no output schema, the description is complete: covers purpose, usage, limitations, and sibling tool distinction.

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 has 100% coverage but description adds context: batching multiple numbers and what the return value is (registered/unregistered status). This adds meaning beyond the schema description.

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 it checks whether phone numbers are registered Signal users, using a specific verb 'check' and resource. It distinguishes itself from sibling tools like 'get_profile', making its purpose unambiguous.

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 tells when to use (before sending to unknown numbers) and when not to use (not for profile details, use 'get_profile' instead). Also notes limitation about privacy-mode accounts, providing clear usage guidance.

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