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

The annotations already declare the safety profile (readOnly=false, destructive=false, idempotent=false, openWorld=false), so the description's job is to add context and it largely doesn't. "Requires MCP 2026-07-28" is an environment prerequisite of some value, but nothing is said about size/format limits, whether re-uploads duplicate, where the image ends up, or authentication needs — for a mutation tool with a free-form schema this is a significant gap.

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?

Two short sentences, front-loaded with the action, with no filler. The brevity is efficient but comes at the cost of substance; the second sentence is cryptic without context and is the only part not already covered by 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?

With no output schema, no parameter documentation, and a free-form input object, the description carries the full burden and does not meet it. An agent cannot determine the expected argument shape or the result of the call from this definition.

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?

Parameter count is 0 with 100% schema coverage, which would normally earn the baseline 4, but the schema is an empty object with additionalProperties:{}, implying the real payload (image data, filename, mime type, target) is expected but entirely undocumented. The description does nothing to describe that payload, so it falls below baseline.

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?

"Upload an image" states a verb and resource, so the basic action is unambiguous, but it is a near-verbatim restatement of the title and name. It gives no scope: what kind of image, uploaded to where (a topic, post, profile, document), and no differentiation from any sibling.

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?

There is no statement of when to use this tool versus alternatives, nor any prerequisites beyond a cryptic version note. The agent is left to infer context — e.g., whether an image must be uploaded before referencing it in a comment or markdown document — with no guidance from the definition.

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