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

Annotations already declare readOnly/openWorld/non-destructive, so safety is covered. The description adds real value beyond that: it discloses the auth requirement ('Needs the user's Cotlet API key with access to this app') and, with no output schema present, describes the returned fields (email, phone, address).

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?

Purpose is front-loaded, but the first two sentences are near-duplicates ('Clients with contact email, phone and address' / 'Returns clients with contact email, phone and address'), wasting space that could carry additional guidance.

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 one-parameter list tool with no output schema, the description covers the essentials: what is returned, that search matches by name, the auth requirement, and a downstream usage hint. Nothing critical an agent needs in order to invoke it is missing.

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 100% and there is a single 'search' parameter already documented as 'Client name.' The description adds the matching semantics ('Search matches the client name'), a marginal gain over the schema, so the baseline 3 holds.

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 names a clear verb+resource: 'Returns clients with contact email, phone and address,' and the tool is unambiguously a client-listing operation. It does not differentiate from sibling client tools (create_client, list_invoices), but the core purpose is immediately intelligible.

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?

It offers partial workflow guidance ('Search matches the client name,' 'Use client_id in create_job'), which implies how and why to call it, but never states explicit when/when-not conditions or names an alternative listing/search tool.

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