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

Annotations already cover read-only, non-destructive, open-world and non-idempotent semantics. The description adds real value beyond them: it discloses that the tool performs a live fetch of the target URL, enumerates the exact attributes and insecure patterns it checks, and explains the non-obvious scoring rule (overall score equals the weakest cookie, with average_score reported separately). It stops short of describing failure behavior, e.g. unreachable URLs or pages that set no cookies.

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 purpose sentence is front-loaded, and the remaining detail is a compact enumeration of inspected attributes, flagged patterns, and output semantics. Every clause carries decision-relevant information; nothing is repeated from the title or schema.

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 an output schema present, the description need not document return shape, yet it still clarifies the most easily misread part of the output (weakest-cookie scoring vs. average). Combined with the enumerated checks and the live-fetch disclosure, an agent has everything needed to call it correctly.

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% and the single 'url' parameter is fully documented as a full URL to audit with an example. The description adds no format, redirect, or authentication detail beyond what the schema already says, so the baseline 3 applies.

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 and resource ('Audit the security attributes of cookies set by any URL') and immediately narrows scope to Set-Cookie headers, which cleanly separates it from broad siblings like security_headers_check and web_security_audit. An agent knows exactly what this tool does without opening the schema.

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 scope statement ('cookies set by any URL', inspection of Set-Cookie headers) implies the usage context, but there is no explicit routing guidance such as 'use this instead of security_headers_check when you only care about cookies' or any exclusions. The agent must infer the boundary from the sibling names.

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