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

Annotations already declare readOnly, idempotent, non-destructive. The description adds valuable context: it requires an agency API key and only searches the calling agency's contacts, which explains scope and authorization. This goes beyond the annotations without contradiction.

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 concise sentences. The primary purpose is front-loaded, followed by usage guidance and constraints. No unnecessary words or repetition.

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 search tool, the description adequately covers the core invocation: query string, auth, and scope. However, it does not explain the 'limit' parameter (though schema gives default/max) nor describe the return format or potential result behavior, which an agent might want to know. Given no output schema, these are minor gaps but still leave the description slightly incomplete.

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 coverage is 50%: only 'query' has a description, and the tool description repeats that query accepts name, company, email, or phone. The 'limit' parameter is completely omitted from both schema and description, so the description fails to compensate for the missing documentation on a parameter with constraints and a default.

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 ('Search'), the resource ('YOUR agency's CRM contacts'), and the searchable fields (name, company, email, phone). It is distinct from sibling tools like find_properties_by_description by focusing on contacts, but does not explicitly name that alternative.

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 specific use cases: 'before logging a note' and 'to check if they're already in the CRM', which gives context on when to call. It also notes the prerequisite of an agency API key. However, it does not explicitly state when not to use it or mention alternative tools like create_contact or search_properties.

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