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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real semantic value by defining what 'valid' means (proves what was said and when) and explicitly bounding the claim (does not guarantee the verdict was right), which prevents an agent from over-reading the result.

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, no waste, with the operational check front-loaded before the semantic caveat. Every clause carries information the agent needs.

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?

An output schema exists, so return values need not be described, and annotations cover the safety profile. The description supplies the interpretation of a valid vs. invalid receipt, but it never says how the jws and receipt_id alternatives relate (which takes precedence, what if neither is given), leaving a small operational gap.

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 the baseline is 3; the schema already explains that jws is a full signed receipt string and receipt_id is an rcpt_ value. The description references valid_until but adds no format, precedence, or mutually-exclusive rules 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 (verify/check) and resource ('Tethered Trust receipt'), then enumerates exactly the three questions it answers: signature ownership, valid_until window, and record drift. That is far more specific than a generic 'check' sibling, though it never names or contrasts an alternative tool.

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?

Usage is only implied through the parameter context ('if someone handed it to you', 'from a check'), which signals the scenario but never states when to reach for this versus other verification-adjacent siblings. No explicit when/when-not guidance or prerequisites are given.

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