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

Description says 'additive, sends no message,' which is helpful, but it directly contradicts the annotation destructiveHint=true. The annotation signals possible destructive behavior, while 'additive' asserts no destruction occurs. Per rubric, this contradiction yields score 1.

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?

Single-sentence description that is front-loaded with the verb and includes the endpoint; every word earns its place. Score 5.

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?

The tool has a nested data object and no output schema, and the description doesn't explain the return value or duplicate handling beyond uniqueness. With the annotation contradiction, the description is not fully complete, though the schema covers parameters. Score 3.

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?

All five parameters have complete schema descriptions (coverage 100%), so the schema does the heavy lifting. The description adds only the email uniqueness note already present in the schema; no additional parameter meaning is contributed. Baseline 3.

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 creates a contact (CRM record) in Bird, with the specific qualifier 'additive, sends no message,' distinguishing it from get/list sibling tools and clarifying it is not a messaging operation. This is a specific verb+resource with additional scope.

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?

Provides clear context that this tool is for adding a new contact, with the uniqueness-by-email constraint, but does not explicitly mention alternatives or when not to use (e.g., if contact exists). Since context is clear but no exclusions or alternative guidance is given, score 4.

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