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

readOnlyHint already declares the safety profile, and the description adds genuinely non-obvious behavior: a hard cap of 50 items and newest-first ordering, plus the fields returned per row. That is useful context beyond the annotations. It stops short of saying whether results are scoped to one coach's account or an org, or what happens past 50 conversations, which keeps it from a 5.

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?

Two sentences, zero waste. The scoping and ordering constraints are front-loaded and the routing to sibling tools follows immediately after.

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 parameters, no output schema, and only a readOnlyHint annotation, the description carries the full burden and does so: it discloses the result cap, sort order, per-row contents, and the follow-up tools. Nothing an agent needs in order to call this correctly 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?

The tool takes zero parameters, so there is nothing in the schema for the description to disambiguate. The description correctly adds no parameter talk and instead spends its words on scope and ordering.

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 the exact resource (the coach's chat conversations), the scope (up to 50, newest first), and what each entry carries (participants and last-message time). It also explicitly separates this tool from get_client_chat_messages (read) and send_message_to_client (reply), so an agent can pick it without opening either schema.

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 second sentence gives an explicit workflow: use this to find a conversation, then get_client_chat_messages to read it, then send_message_to_client to reply. Alternatives and their selection conditions are named rather than left to inference.

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