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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description's contribution is disclosing what the payload contains, including a 'private note,' which usefully signals sensitive data. It says nothing about visit-history truncation behavior beyond what the schema states.

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?

A single front-loaded line with zero filler, so nothing wasted. It is a verbless noun phrase rather than a sentence, which makes it slightly terse for a tool that has alternatives to disambiguate from.

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?

With no output schema, the description carries the return-value burden and does so by enumerating the card's contents. For a 2-parameter read with full schema coverage, that is close to sufficient; a note on how visits_limit interacts with the returned history would close the remaining gap.

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%, so client_id and visits_limit (with range, default 20, max 100) are fully documented in the schema. The description only implies visits_limit through the phrase 'visit history' and adds no syntax or format detail beyond the structured field.

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?

Names the resource (a single client card) and enumerates its contents: contact details, private note, counts, visit history. That is clear and distinguishes it from bulk siblings implicitly, but it never states the verb or explicitly contrasts with list_clients/find_client, which is the main confusion risk here.

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?

The description offers no when-to-use or when-not guidance and names no alternative. The only routing hint, 'From list_clients or find_client,' lives in the schema for client_id, not in the description, so an agent must open the schema to learn the lookup flow.

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