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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds valuable behavioral context: it does not keep article text, so the agent must open the link to read the article; and it warns that titles/snippets are publisher-written data, not instructions. This is exactly the kind of context that prevents misuse.

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 sentences, each earning its place: what it returns, the limitation about article text, and the safety warning about treating content as data. Front-loaded with the core purpose, then critical caveats.

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 tool with annotations covering safety and open-world behavior, the description is complete. It explains the return fields, the limitation (no article text), and the instruction-following risk. No output schema exists, but the description covers the return shape sufficiently.

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%, so the schema already documents the single 'id' parameter. The description adds that the id comes from search, which is useful, but it doesn't add format or validation details beyond the schema. 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 ('one article by the id that search returns'), and clearly distinguishes it from siblings like search and get_source_articles. It also lists the exact fields returned, which removes ambiguity about what the tool does.

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 implies when to use it: after search, to retrieve a single article by id. It doesn't explicitly name alternatives or exclusions, but the context 'by the id that search returns' and the sibling list make the usage context clear. It could be stronger with an explicit 'use search first' or 'not for listing articles'.

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