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

The description discloses several behavioral aspects beyond annotations: the direction (inbound conversion vs. generation), the file size limit (10 MB), quota impact (counts against monthly render quota), and authentication requirement (Kamy API key with `render` scope) with a fallback behavior. Annotations are minimal (readOnlyHint: false, destructiveHint: false), so the description carries the full burden and does so thoroughly, far exceeding what annotations alone provide.

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 a single paragraph of 6 sentences, each serving a distinct purpose: defining the action, explaining how input type detection works, distinguishing from generator siblings, describing the return value and downstream usage, noting quota and size constraints, and specifying authentication requirements. Nothing is redundant, and all information is essential and well-ordered, earning every sentence its place.

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?

Despite having no output schema, the description provides a complete picture: it lists the return fields (id, url, bytes, durationMs, name), explains the conversion direction and constraints, covers quota and authentication, and links to sibling tools for downstream operations. The parameter richness (3 params, 100% coverage) and sibling context are fully leveraged to make the description self-sufficient for agent understanding.

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 baseline is 3, but the description adds significant value by explaining the relationship between filename and input type detection, clarifying that the name parameter defaults to the source filename, and describing the purpose of fileBase64 (pass bytes base64-encoded). This transforms basic schema definitions into actionable guidance, fully compensating for any potential ambiguity.

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 clearly states the tool converts .docx, .xlsx, or .csv files to PDF, specifying the verb 'Convert', the resource 'file', and the output format. It distinguishes this tool from siblings like render_docx (which generate new documents from structured data) and render_pdf (builds from a template), making its purpose unambiguous and unique.

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 explicit guidance on when to use this tool versus alternatives, naming render_docx, render_xlsx, render_pptx, and render_pdf as tools that generate documents rather than convert existing ones. It also explains that the returned id can be fed into merger/split/sign tools, and flags the constraint that files over 10 MB are refused because bytes pass through the tool call. This covers both when-to-use and when-not-to-use scenarios comprehensively.

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