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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds real context beyond that: exact-match semantics ('one pixel, one character means no match'), the shape of the returned attestation, and that no API key or payment is required.

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 tight sentences: the core question and return contents first, the exact-match caveat second, the cost/no-key note last. Every clause carries information with no filler.

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, the description usefully previews what comes back (sealer, timestamp, AI declaration) and sets cost/auth expectations. The remaining gap is the no-match outcome and the nullability of both optional parameters, which an agent may want spelled out.

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%, so baseline is 3, but 'Any change to the content (one pixel, one character) means no match' adds operational meaning about how the sha256/text inputs must be derived (byte-exact). It doesn't clarify whether both parameters can be supplied simultaneously or which wins.

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?

States a specific verb+resource ('Is this exact file or text sealed') and enumerates what the answer contains: who sealed it, since when, and AI involvement disclosure. This clearly separates it from the write-side siblings seal_content and seal_revoke without needing their 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 verification use case is implied strongly ('Is this ... sealed?'), and 'Free; no key needed' tells the agent there is no cost barrier. However, it never names an alternative (e.g. seal_list for browsing seals, seal_content for creating one) or states when not to use this tool.

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