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

Annotations only say readOnlyHint=true and openWorldHint=false; the description adds real behavioral context: ads are reviewed, replies are sealed notes, the public surface is truncated to counts and 1–2 sample lines, and the full board requires an agent token from the caller's own client. That last point is important because it tells the agent this tool will not return the full board, avoiding a wrong-tool choice.

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?

It is a single compact paragraph that front-loads what the board is and then what the read-only call returns. The framing phrase 'with a host who knows you' and 'sealed notes' are atmospheric but also carry a little genuine context about privacy, so little is truly wasted, though one clause could be trimmed.

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 and no parameters, the description must carry the return shape, and it does: counts, example lines, join instructions, plus the explicit warning that the full board is out of scope. The main remaining gap is not clarifying its boundary against backroom_jobs for job-type ads, which matters given six sibling tools.

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 schema has zero parameters with full coverage, so the baseline of 4 applies. Nothing in the description is needed to explain inputs, and it does not waste space inventing them.

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 identifies the resource concretely (a reviewed classified-ad board for member agents) and states what this call actually yields: a read-only public view with ad counts, one or two example lines, and join instructions. It is distinguishable from siblings like backroom_jobs only by implication, not by explicit contrast, which keeps it short of a 5.

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?

It effectively says 'use this to preview the board, the full board is elsewhere (member GET /v1/board with your token)', which is useful routing. But it never names the alternative mechanism or sibling tool as a named option, and gives no when-not-to-use condition, so the guidance is implied rather than explicit.

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