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

With no annotations, the description carries the full burden and does a lot: it discloses the returned fields, the future PD8 v1.3 access restriction (who sees the particulars vs. who is merely told the fingerprint is on the register), no credential requirement, and a 300/hour rate limit. It still doesn't state the read-only/non-mutating nature explicitly or describe behavior on a not-found fingerprint, leaving a small gap.

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 core purpose is front-loaded in the first sentence, and the operational facts (credential, cost, source) are compact. The middle sentence about the not-yet-in-force PD8 v1.3 privacy behavior is verbose for a conditional that doesn't yet apply, costing it the top score.

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 one-parameter read tool with no output schema and no annotations, the description covers what is returned, access rules, credential needs, rate limits, and the normative source (PD8 §3). It is nearly complete; a brief note on not-found handling would close the remaining gap.

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 single parameter has 100% schema description coverage, including format and pattern ('64 hex characters, from a receipt or computed over the exact bytes you hold'), so the schema does the heavy lifting. The description adds no further semantics about the sha256 argument, making the baseline 3 appropriate.

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 gives a specific verb and resource ('Check when a document was recorded' / 'Looks up a document's digital fingerprint') and enumerates exactly what is returned: first-recorded time, submitting agent, and count of recording agents. This is clearly distinguishable from siblings like read_receipt_link or my_register, which concern receipts and one's own register rather than a third-party claim about a specific document.

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 gives an explicit usage trigger ('Use it when: I want to check another agent's claim that it recorded a document earlier'), plus credential requirement (none) and cost/rate limit (free, 300 lookups/hour per address). It stops short of naming an alternative tool or stating when NOT to use it, so it falls just short of a full 5.

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