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

Annotations already mark the operation as non-read-only, idempotent, and non-destructive; the description adds useful context by describing the signed receipt, the public verification URL, and the subscription requirement. No contradiction with 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?

Two concise sentences front-load the core action and output, then add idempotency and auth requirements. Every sentence carries meaningful 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?

For a two-parameter tool with no output schema, the description provides the essential return concept (a signed receipt with public verify URL), idempotency, and auth prerequisite. It does not describe the receipt structure in detail, but that is unlikely to block correct invocation.

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 documents both parameters fully (100% coverage), including the header-precedence behavior for api_key, so the description does not need to add much. Its mention of needing a subscription loosely reinforces api_key's purpose but adds little beyond the schema.

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 ('Seal'), the target resource ('an open run'), the output ('one signed Run Receipt covering every entry, with a public verify URL'), and the idempotent behavior. This clearly differentiates it from sibling tools like open_run or record_run_entry without needing to inspect 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?

It clearly indicates this is for an open run that should be closed into a receipt, and idempotency covers repeated calls. It names the subscription requirement, but it does not explicitly name alternative tools or say when not to use it, so it stops just short of full guidance.

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