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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true. The description adds only the resource name ('Seal signing key') but discloses no additional behavioral traits such as authentication requirements, latency, caching behavior, or what happens if the key is unavailable. For a simple fetch, this is minimal value beyond the annotations.

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 consists of a single, efficient sentence with no filler or redundant information. It is perfectly sized for the task and immediately front-loaded with the core action.

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?

Despite the tool being simple (0 parameters, no output schema), the description omits crucial details about the return value (e.g., format, encoding, whether it's a raw key or a JWK) and does not explain what the 'Seal signing key' is used for. An agent would lack the context needed to interpret the result or decide if this tool is appropriate without prior knowledge.

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?

There are no parameters (schema is empty with 100% coverage), so the description does not need to elaborate on parameters. The baseline of 4 is appropriate since the description does not mislead and the absence of parameters is clear. No extra parameter documentation is required.

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 the specific verb 'Fetch' and explicitly names the resource as 'the published Seal signing key,' clearly distinguishing this tool from siblings like decode_receipt, verify_receipt, and get_transparency_proof. The purpose is unambiguous and directly aligns with the tool name.

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 no guidance on when to use this tool versus alternatives (e.g., should it be used before verifying receipts? Are there prerequisites?). It neither states typical scenarios nor excludes inappropriate use. There is no mention of siblings or constraints.

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