image

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

No annotations are supplied, so the description carries the disclosure burden, and it does reveal the return shape (300px thumbnail URL plus full-resolution original URL) and the no-image fallback behavior. It omits any note on rate limits, auth, or whether the URL is hotlink-safe, which keeps it short of a 5 for a zero-annotation tool.

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?

Front-loaded with the core return contract, then the disambiguation from `summary`. The parenthetical use-case list ('cards, Telegram posts, slide decks, README hero images') is slightly padded and could be trimmed without losing meaning.

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?

There is no output schema, so the description's explanation of the two returned URLs and the empty-image case does real work. Combined with a fully documented two-parameter schema, an agent has everything needed to call and interpret the result.

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 both params (lang enum, title) are fully documented in the schema, so the baseline of 3 applies. The description adds no syntax or format detail about `title` handling (e.g. underscores vs spaces) beyond the schema's own example.

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 precise verb and resource ('Get just the lead image for a Wikipedia article') and immediately names what it returns. It explicitly differentiates itself from the sibling `summary`, which embeds the thumbnail inline, so an agent can route correctly without opening either 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?

Gives a concrete when-to-use condition ('when you want the article's image for embedding elsewhere ... without the surrounding summary text') with example scenarios, and names the alternative tool (`summary`) plus the reason to prefer this one. The contrast is explicit rather than inferred.

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