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

Annotations only declare readOnlyHint and openWorldHint; the description goes well beyond by disclosing the paid model ($0.005 USDC per call via x402), hard capacity limits (20 files / 20 MB in, 50 files / 20 MB expanded), and the store surcharge. It does not discuss failure modes or auth handshake details, so it falls just short of full behavioral coverage.

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 dense sentences, front-loaded with the primary capability and limits, with pricing appended last. Every clause carries actionable information (limits, input formats, cost, purpose); no padding.

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 seven-parameter tool with no output schema, the description covers both modes, capacity limits, input forms and cost, which is what an agent needs to choose and call it. It stops short of clarifying what the return looks like per mode (base64 vs share links vs binary), which the schema only partly covers.

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 71%, so the schema carries much of the load, but the description adds real meaning: accepted input forms for 'files' (URL or base64), the count/size bounds tied to the mode, and the cost semantics of 'store'. It leaves 'format', 'archive_name' and 'file_base64' unexplained, so it only partially compensates.

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 specific verbs (zip, list, extract) and the resource (files/archive), plus the two operating modes an agent must choose between. No sibling tool does archiving, so the absence of explicit sibling differentiation is not a gap here.

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 frames the two clear use contexts: build an archive from up to 20 inputs, or inspect/extract an existing zip 'so an agent can read what is inside.' It does not name alternatives or exclusions, but no near-sibling exists to route away from, so the implied guidance is sufficient.

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