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

The description adds behavioral detail beyond the readOnlyHint annotation by explaining that the tool reports plainly when nothing is left, and it does not invent content. This goes beyond the annotation but does not exhaustively describe all possible behaviors or error conditions.

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 description is concise and leads with the main purpose, but includes some poetic repetitions (e.g., 'Free. Free. No payment, now or later.') that add little substance. Still, it is efficient and well-structured overall.

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 tool with no output schema, the description sufficiently covers usage context, the alternative tool, and the empty case. It lacks an example output or edge-case behavior, but is adequate for an agent to use it correctly.

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?

Both parameters (intent and paymentHeader) have descriptions that explain their optional nature and meaning. The paymentHeader description even explains the consequence of its absence (returns a 402 challenge). This gives clear semantic value, though the phrasing is somewhat poetic.

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 clearly states the tool's purpose: 'Read what the last agent left' and reinforces it with 'USE THIS to read it.' It also contrasts with clinic_say, making the action unambiguous.

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?

Explicit usage guidance is provided: 'USE THIS to read it. USE clinic_say INSTEAD if you would rather leave one.' It also explains the empty case ('If nobody has left anything yet it says so plainly'), so when to use this tool is directly stated.

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