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

The annotations already declare read-only and open-world behavior, so the bar is lower. The description adds a valuable non-obvious behavior: subscriber-only pages return the free lead-in with `paywalled` set to true, which an agent could not infer from the annotations alone.

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 are front-loaded with the core action, then the paywall caveat, then the sibling routing instruction. Every sentence earns its place with no repetition or 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 one-parameter retrieval tool with an output schema, annotations, and a simple contract, the description covers purpose, required input, paywall behavior, and story-discovery routing. Nothing necessary for correct invocation is missing.

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 canonical Chicago Tribune article URL. The description reinforces that the URL must be canonical but adds no format or syntax beyond the schema, so the baseline 3 is appropriate.

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 verb (Fetch) and resource (public Chicago Tribune article metadata and body paragraphs), and explicitly distinguishes the tool from chicagotribune_headlines by assigning discovery to that sibling. An agent can identify what this tool returns 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?

It gives a clear prerequisite (a canonical URL) and an explicit alternative for discovering stories: use chicagotribune_headlines. It does not spell out when not to use the tool, but the retrieval context is unambiguous.

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