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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds meaningful context beyond annotations: reports expire after 30 days, the token is a 16-character code at the end of a URL, and no sign-in is required. This is useful behavioral information an agent otherwise would not know.

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?

Three concise sentences with no filler. The core purpose is front-loaded, followed by usage context, expiration, and auth note. Every sentence adds value.

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 single-parameter read-only tool, the description covers purpose, token extraction, expiry, and authentication. It doesn't describe the report content or error behavior, but given the simplicity and strong annotations, nothing critical is missing for 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 describes the token parameter at 100% coverage, including accepting the full report URL. The description adds complementary meaning by explaining where the token comes from and how to recognize it, which helps the agent validate or extract the parameter in real user inputs.

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 states a specific action ('Fetch a check report') and a specific resource ('by its share token'), and clarifies the token's format and location. It clearly distinguishes this from siblings like check_site by framing it as retrieval of an already-run report rather than initiating a check.

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?

Explicitly tells the agent when to use it: when someone pastes a report link or asks about a check that was already run. It also gives a direct alternative behavior ('instead of checking the site again'), which is strong usage guidance relative to the sibling tools.

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