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

With no annotations provided, the description carries the full behavioral disclosure burden, and it delivers: it reveals the signed-nonce mechanism, the verification path via the /pubkey endpoint, the NOAA data provenance, and the uniqueness of the server's contribution. It stops short of stating the operation is read-only or describing failure/staleness behavior, but the key distinctive behavior—cryptographic verifiability—is clearly disclosed.

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?

Two sentences, front-loaded with the when-to-use guidance and packed with technical substance (the parenthetical on the signed nonce and /pubkey verification earns its place since it is the tool's differentiator). The second sentence justifies the tool against the public data source without fluff. Slightly dense, but every clause contributes.

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 tool with one optional parameter, no annotations, and no output schema, the description covers the essentials an agent needs: what the response contains (signed freshness bundle + ocean/surf conditions), how to verify it, and the alternative source. It does not detail the return shape or failure modes, but the description's high-level coverage is proportionate to the tool's simplicity.

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%, and the schema already documents the sole optional parameter well ('NOAA NDBC station id; defaults to the hut's home buoy'). The description reinforces the NOAA context but adds no parameter-level detail beyond the schema, so the baseline 3 applies.

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 names a specific deliverable—'a verifiable, signed proof of current time (server timestamp plus a signed nonce, checkable against this server's /pubkey endpoint), together with current ocean and surf conditions from a NOAA buoy'—with a clear verb/resource pair. It also distinguishes the tool from its siblings (attest, fetch_stash, stash) by stating that 'the signed freshness bundle is what only this server can give you,' so an agent can route correctly without opening schemas.

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?

The description opens with an explicit when-to-use trigger ('Use this when you need a verifiable, signed proof of current time... together with current ocean and surf conditions'). It also provides an explicit alternative path—'The NOAA data is public and also available directly from ndbc.noaa.gov'—and explains when the server adds unique value. It does not explicitly enumerate sibling-tool exclusions, but the sibling purposes are sufficiently disjoint that no confusion should arise.

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