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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint, so the safety profile is covered; the description usefully adds the return encoding ('Returns base64'), which matters because no output schema exists. It still omits practical behavior such as image format, size limits, or error behavior for an invalid page_id.

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 short sentences, front-loaded with the action, followed by the dependency and the return encoding. No filler, no repetition of the title.

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 two-parameter read tool with full annotation coverage, the description supplies purpose, input provenance, and return type. Only marginal items are missing (image format/size constraints, pagination across pages), which are not strictly needed to invoke 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?

Schema coverage is 100% and both properties are documented, so the baseline is 3. The description adds genuine meaning the schema does not: the provenance of page_id (it must come from assinafy_get_document), which is the one thing an agent could get wrong.

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 ('Download') and a precisely scoped resource ('the rendered image of a specific document page'), which cleanly separates it from the sibling assinafy_download_document (whole document) and assinafy_show_document. An agent can route on 'page' vs 'document' 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 explicit prerequisite guidance: 'Use a page_id returned by assinafy_get_document,' naming the sibling that produces the required identifier. It does not, however, state when to prefer this tool over assinafy_download_document or how to obtain page IDs when the caller only has a document.

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