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

Annotations already provide readOnlyHint=true, idempotentHint=true, and destructiveHint=false, and the description aligns with them while adding real behavioral value: fetching is free and uses stored data, a ready article contains both markdown and HTML, and markdown is the source of truth. It also discloses that the list mode reveals prepaid balance, going beyond the schema.

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 cover the primary action, the alternative list mode, format details, and cost behavior, all without fluff. The main usage is front-loaded, and each sentence contributes useful information, though the 'pay-as-you-go' phrasing adds minor ambiguity alongside the 'Cost: FREE' clarification.

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 tool is simple, has an output schema, and is backed by rich annotations. The description covers polling workflow, the two returned formats, the source-of-truth relationship, and cost behavior, so an agent has everything needed to select and invoke this tool 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%, so the schema already documents both parameters well. The description reinforces that article_id comes from generate_article and that omitting it triggers listing, but it adds little beyond the schema's own text. 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 starts with a specific verb and resource, 'Fetch a pay-as-you-go article by id,' and also covers the list mode when article_id is omitted. It explicitly ties the id to generate_article, which differentiates it from the sibling generation tool and clarifies the article lifecycle.

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 clear usage context: poll with the id returned by generate_article, or omit the id to list recent articles and prepaid balance. It doesn't spell out exclusions, but the reference to generate_article and the dual-mode behavior make the intended workflow obvious.

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