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

Annotations only declare the safety profile (readOnly=false, destructive=false, openWorld=false, idempotent=false). The description adds genuinely non-obvious behavior: the server downloads the URL, per-source size caps (3MB base64, 10MB URL), magic-byte validation rather than extension trust, and refusal of internal/private addresses (SSRF guard). These are real additions, but the return contract is only summarized as 'returns uploadId', with no mention of error shapes or whether partial/failed uploads leave residue.

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 action and both input modes, then constraints, then routing and prerequisites — a sensible priority order. It is dense with parentheticals in a single paragraph, which costs a little readability, but no sentence is filler.

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 4-param upload tool with no output schema, it covers the source modes, size limits, validation, auth requirement, SSRF policy, downstream handoff, and a sibling alternative. An agent has everything needed to call it correctly on the first attempt.

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%, so the baseline is 3, and the description still adds meaning: the per-parameter size ceilings (3MB base64 vs 10MB URL) and the byte-level format restriction are not in the schema. The url-vs-base64 exclusivity is already in the schema text, so that part is repetition.

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 and resource (upload one product picture) plus both accepted sources (public URL downloaded server-side, or base64). It explicitly distinguishes itself from the sibling createUploadSessionTool for chat-attached files, so an agent can route 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 when-to-use (URL or base64 for agents that can read files) and when-not-to-use (chat attachments go to createUploadSession). It also names the downstream consumers (setProductImages, createRikmaProduct) and the membership prerequisite, leaving nothing to inference.

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