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

Annotations only declare readOnlyHint and openWorldHint, but the description adds a genuinely non-obvious runtime behavior: subscriber-only pages return the free lead-in with the `paywalled` field set to true. That paywall/partial-content disclosure goes meaningfully beyond the structured annotations.

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 front-loaded sentences: purpose first, then the paywall caveat, then sibling routing. No filler and every sentence carries distinct information.

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?

A read-only, single-URL fetch tool with a full output schema, so return structure needn't be described. The description covers purpose, the notable paywall behavior, and alternative tools, leaving nothing an agent needs 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?

Only one parameter (url) at 100% schema coverage, and the schema already documents it as the canonical article URL. The description restates 'from a canonical `url`' without adding format, validation, or example details beyond the schema, 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 (Fetch) and resource (New York Daily News article metadata and body paragraphs) from a canonical url, and distinguishes the tool from its headline/section siblings. An agent can identify exactly what is returned 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?

Explicitly routes the agent: 'Use nydailynews_headlines for story lists or nydailynews_sections to browse topics,' which names the alternatives and the conditions under which they are preferred. When-to-use-this is clear from contrast with the two named siblings.

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