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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, which cover the safety profile. The description adds valuable behavioral context by explaining that the tool returns a URL and that the caller must fetch the binary PDF directly via browser or curl, making the two-step nature explicit. This goes beyond the annotations and helps the agent know the output is not the PDF itself.

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?

The description is extremely concise, using only two sentences to convey the core functionality and required next step. It front-loads the main action and avoids any fluff or repetition. The structure is efficient and easy to parse.

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 relatively simple, and the output schema exists, but the description leaves gaps. The 'project' parameter is ambiguous, and the 'Mapbox static-tile image URL' wording is opaque. The description does not explain the relationship between the URL and the PDF, nor does it clarify the values for 'project' or 'lang'. Given 0% schema description coverage, the description should have provided more detail to make the tool fully understandable.

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 0%, so the description must compensate. It adds some meaning by stating that title is required and that project/lang are optional for non-English Wikimedia projects, which helps clarify their role. However, it does not thoroughly explain the format expected for 'project' (e.g., 'wikipedia' vs 'wiktionary') or how 'lang' should be specified, leaving ambiguity for an agent trying to invoke the tool correctly.

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 that the tool returns a URL for a PDF download of a Wikipedia article, using the verb 'Returns' and naming the resource. It also distinguishes itself from sibling page_* tools by being the only one that returns a PDF download URL. However, the phrase 'Mapbox static-tile image URL' is confusing and could mislead about the actual output format.

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 provides implicit usage context: it is for retrieving a PDF of a Wikipedia article, and it mentions optional project/lang for non-English projects. It also instructs the caller to fetch the PDF from the returned URL, which is a clear usage step. However, it does not explicitly state when to use this tool versus alternatives like page_html or page_summary, nor does it provide any exclusions.

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