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

Beyond annotations (which are minimal), the description reveals multiple behavioral traits: the dual upload mechanism, size limits, time constraint, return value shapes for both scenarios, MIME restriction enforcement, and authentication requirements. This fully informs the agent about the tool's non-obvious behaviors and side effects.

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, dense paragraph, but every sentence adds essential information without redundancy. It front-loads the core purpose (storing assets and returning references). A slight improvement would be structuring into separate sentences or bullets, but it remains efficient and scannable.

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 no output schema, the description fully specifies the return object shape for both modes (`{ id, assetRef, bytes, uploaded: true }` and `{ uploadUrl, uploadMethod, uploadHeaders, expiresAt, uploaded: false }`). It covers auth, size caps, timeouts, MIME restrictions, and integration with other tools (render_pdf/render_html). The description leaves no major information gaps for an agent to safely and correctly invoke the tool.

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?

The input schema covers all 4 parameters with descriptions (coverage 100%). The description adds extra semantics: it explains that `contentBase64` triggers immediate upload vs. deferred, that `sizeBytes` is auto-computed when `contentBase64` is present, and that `contentType` must be from the enum. This enriches the schema's baseline by providing usage context and dependencies between parameters.

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 stores an asset (image, font, PDF) in the account's asset bucket and returns a `kamy://asset/<id>` reference. It specifies the verb 'store', the resource type, and the output, and distinguishes itself from sibling tools by being the only upload-focused tool.

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 explicitly explains two usage modes: supplying contentBase64 for inline uploads (capped at 5 MB) or omitting it to receive a pre-signed URL for large files (up to 100 MB, 15-minute window). It also states the acceptable MIME types, the required API key scope (`uploads:write`), and implies when this tool should be used (for assets needed in render_pdf/render_html templates). This provides clear situational guidance.

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