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

Annotations already declare readOnlyHint, openWorldHint, and destructiveHint=false, so the safety profile is covered. The description adds real value beyond that: the sort order (most recent first), the per-item fields returned, the scope exclusion for appointment-notification replies, and the Cotlet API key/access requirement.

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?

The purpose is front-loaded, but the first two sentences restate the same content (last message and unread status) with overlap, and the auth note is bolted on at the end. It is acceptable but not tightly worded.

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 read-only list tool with no output schema, the description covers the essential ground: what is returned, ordering, a scope caveat, and auth prerequisites. Only minor gaps remain (pagination/limit behavior beyond the schema), so it is nearly complete.

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?

With 100% schema description coverage, the schema already documents both limit and unread_only, so the baseline is 3. The description meaningfully clarifies unread_only's intent ("see what needs an answer") but adds nothing about limit, so it does not exceed the baseline.

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 (list) and resource (Connect chats with clients) plus the payload shape (last message + unread status, most recent first). It is clear what the tool returns, though it never names the sibling reply/action tool (vagaro_reply_to_client) to sharpen the read-vs-reply distinction.

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?

"Set unread_only to see what needs an answer" gives an implied usage cue, and the exclusion of appointment-notification replies narrows scope. However, there is no explicit when-to-use statement or comparison to an alternative tool; the guidance is inferred rather than stated.

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