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

With no annotations, the description carries the full burden and does an excellent job: it discloses rate limiting, unsigned vs. signed attestations, required payment headers for signing, and the fact that the same tool call can be upgraded. It also enumerates the returned data, giving an agent a solid behavioral model beyond the schema.

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 compact for the amount of behavior it conveys. It front-loads the core purpose, then lists concrete return values, then adds rate-limit/payment details. Every sentence pulls weight and even the nested payment/transport details are clearly scoped to when you need a signed attestation.

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?

Given there is no output schema, the description compensates by listing the relevant return data (HTTP status, Last-Modified/ETag, SHA-256, change flag, attestation). It also covers the key operational context: free tier limitations, rate limits, and pricing. The sibling tools are obviously different in scope, so little about invocation is missing.

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 already covers both parameters at 100%, and the description adds value by explaining how prior_hash is used ('whether the content changed versus a prior hash') and connecting the URL to HTTP status/ETag/Last-Modified. This goes beyond the schema's terse field descriptions and reinforces the mechanics of the comparison.

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 uses a specific verb+resource: 'Check that a URL is live and its data is fresh before your agent acts on its contents.' It names concrete outputs (HTTP status, Last-Modified/ETag, content SHA-256) and frames the tool as a 'freshness oracle,' which clearly sets it apart from the sibling verification tools focused on business, claims, and prices.

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 provides clear usage context: use this tool to verify URL liveness/freshness before acting on content. It also mentions an alternative and equal path (POST /verify/freshness over HTTP) and the condition for the paid tier. It does not explicitly say 'use verify_business/claim/price for those domains,' but the domain-specific wording makes the intended use unmistakable.

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