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

Annotations already declare readOnlyHint=false, destructiveHint=true and idempotentHint=true; the description adds real context on top by stating the file is discarded and that installed modpacks are out of scope, which defines the blast radius. It stops short of saying whether a partially installed state or a retry after timeout is safe, but the idempotentHint covers the repeat-call case.

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 sentences, zero waste. The scope and the exclusion plus the pointer to deleteModpack are all front-loaded and none of it repeats the annotations verbatim.

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, the description could say what a successful cancel returns (or whether the upload record disappears entirely), and it doesn't state that the key/uploadId pair must be the ones from startModpackUpload. Neither gap is likely to cause a wrong call for a cancel operation with annotations already declaring destructiveness and idempotency.

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 description says nothing about key, uploadId, or serverId — it relies entirely on the schema. The visible schema does carry per-property descriptions ('key returned by the start call', 'id field from listServers'), which mitigates the reported 0% coverage, but the description itself contributes no parameter meaning, so this stays at the 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?

Specific verb, resource, and lifecycle state, with explicit sibling contrast.

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 both the positive condition (unfinished / checked-but-not-installed upload) and the negative condition (an installed modpack is not affected), then routes to the correct alternative (remove it with deleteModpack). No inference required about when to pick this tool.

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