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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered and the bar is lower. The description still adds real context: permission-scoped visibility ('rooms the person can see'), newest-first ordering, and the per-hit line format (author, time, room, message id). It does not cover result-volume behavior such as how limit interacts with more matches, which keeps it at a solid but not exceptional 3.

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 sentences, each earning its place: scope/ordering/result shape first, then when-to-use, then the follow-up navigation. No filler or restatement of the name.

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?

No output schema exists, and the description compensates by describing the return format precisely (one line per hit with author, timestamp, room, message id) along with sort order and visibility scope. An agent has everything needed to call it and to act on results.

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 100%, so the schema already documents limit, query syntax, roomId and workspace, making the baseline 3. The description only loosely reinforces roomId ('or in one room'), while the parameter names it cites (before, from) belong to rooms_read, not this tool.

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 ('searches the messages in the rooms'), plus scope ('the person can see, or in one room'), ordering ('newest first') and result shape. Explicitly separates itself from rooms_read by noting hits may be older than what rooms_read shows.

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?

Gives concrete trigger conditions ('when someone asks what a group said about something, when it was decided, or who brought it up') and names the alternative (rooms_read) with the recency condition that distinguishes them. Also spells out the follow-up path via rooms_read with before/from.

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