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

Annotations are empty, so the description carries the full burden of behavioral disclosure. It explicitly states the tool is deterministic and makes no external calls, which is critical for agent safety. Mentioning the cost adds transparency, though it does not discuss potential side effects, which are unnecessary for a pure extraction operation.

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 is three concise sentences with no redundancy. The purpose is front-loaded, and the additional details about determinism and cost are presented compactly, making it easy for an agent to scan.

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?

The description covers the purpose, output content (entity types), and operational characteristics (determinism, cost). Since there is no output schema, listing the entity types gives a reasonable picture of the return structure. No critical detail is missing for an agent to call the tool correctly, though an example or explicit return format would push it to a 5.

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 only parameter, text, is already documented in the schema with its max length. The description reinforces that the input is 'unstructured text' and lists the entity types it will extract, providing context about the function's behavior. However, it does not add new formatting or syntax details beyond the schema, so it remains at the baseline for high schema coverage.

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 clearly states the tool extracts structured entities from text and enumerates the specific entity types (emails, URLs, phone numbers, etc.). This distinguishes it from sibling tools like health, timestamp, and uuid, which likely handle different text operations.

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 the sibling tools. It only explains what it does and its reliability/cost, leaving the agent to infer usage context without explicit alternatives or exclusions.

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