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

readOnlyHint=true already tells the agent this is a safe read, and the description goes further: it discloses the visibility model (never visible to the client, other coaches, or admins) and the empty-string-return behavior when nothing is written. It does not cover whether an inaccessible clientId errors or returns empty, which is the main remaining gap.

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 short sentences, front-loaded with purpose, then privacy semantics, then the return behavior and the parameter instruction. No filler; every clause carries information.

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 single-parameter read-only tool with no output schema, the description covers what it returns (free text, empty string when absent) and how to call it (pass the client's user _id). Privacy semantics add context no structured field provides; only failure/error behavior is left unspecified.

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 0%, so the description must carry the parameter meaning, and it does: it specifies the client's user _id rather than a generic client record id, which matters in a system where many sibling tools take clientId-style parameters. It stops short of naming the parameter key explicitly.

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?

States a specific verb and resource ('The coach's PRIVATE notes on one client') and identifies the content type (free text) and scope (one client). The get/set pairing with the sibling set_coach_client_notes is unambiguous from the names plus this description.

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 purpose implies when to use it (retrieving notes before a session or check-in), but there is no explicit when/when-not guidance and no alternatives named, such as get_coach_client_desk_record or get_client_profile. An agent must infer usage context.

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