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

The description discloses the confirmation link mechanism, proof of ownership, and what happens if the email is already in use. Annotations only provide readOnlyHint and destructiveHint, so the description adds full behavioral context.

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 that are front-loaded: action and context first, then the flow, then usage guidance. No wasted words.

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 covers purpose, usage, behavior, and edge cases completely.

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 only parameter 'email' is fully described in the schema (100% coverage). The description adds no new semantic detail beyond the schema, so baseline 3 is appropriate.

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 specific verb 'attach' and resource 'email address to the signed-in user's phone-keyed TuLugar account', with context about WhatsApp accounts. It distinguishes itself from siblings by addressing a unique need.

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 states when to use (accounts without a real email), provides step-by-step instruction ('Ask for the email, confirm it back to them, then call this'), and explains behavior for edge cases (email belongs to another account).

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