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

Annotations are all false and provide minimal signal, so the description carries the burden. It discloses deduplication by email (returns existing contact), creation as unassigned, flagging for attention, and the requirement of an agency API key. These go well beyond annotations, though it doesn't specify the return format for a new contact.

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, each carrying distinct value: purpose, dedup behavior, and side effects/requirements. No fluff, front-loaded with the core action. Efficiently structured.

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 description covers most operational context: purpose, dedup, post-creation state, and auth requirement. The only notable gap is the lack of a clear statement about the return value for a fresh creation (it only mentions 'returned' in the case of duplicate). Given no output schema, a bit more explicit return description would make it fully complete.

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 all parameters are already described in the schema. The description adds no parameter-specific meaning beyond what the schema provides (e.g., email is for dedup is already in the schema). 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 uses a specific verb ('Add') and resource ('contact to YOUR agency's CRM'), and clarifies the types of persons (buyer, owner, enquirer). It is clearly distinguished from sibling tools like find_contacts (search) and create_listing (different resource).

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 the tool: 'Use when the agent wants to save a person'. It does not explicitly list alternatives or conditions to avoid, but the guidance is clear and the dedup behavior is called out. Missing explicit 'when not to use' prevents a 5.

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