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

Beyond readOnlyHint=true, the description discloses important behavior: the returned URL is valid for 5 minutes, the host downloads bytes with the same MCP credentials, permissions are rechecked on every call, OAuth is supported, no OSS direct link or key is returned, and the URL is non-shareable. This is substantial operational and security context not present in the annotations.

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 compact and front-loaded, starting with the login prerequisite and then the materialId-to-GET-address sequence. Every clause adds operational meaning: expiration, credential scope, permission recheck, OAuth support, and sharing restrictions.

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 simple read-only download-channel tool with no output schema, the description covers the returned artifact, temporary URL lifetime, authorization checks, and sharing constraints. The main remaining gap is that activityRef is not described, but overall it gives an agent enough context to invoke the tool correctly.

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 description coverage is 0%, so the description must compensate for undocumented parameters. It usefully explains that materialId comes from list_activity_materials, but it does not explain the format or meaning of activityRef, leaving one of two required parameters underspecified.

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 names the specific operation: obtain a temporary 5-minute GET download address for an activity material. It distinguishes this from list_activity_materials by explaining that materialId must first come from that list, and that the host downloads the real bytes rather than the tool returning a file directly.

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?

It gives clear usage sequencing: login, obtain materialId from list_activity_materials, then call this tool for the GET address. It also states permission rechecks happen each time, OAuth is supported, and the link must not be shared or forwarded, though it does not name explicit alternatives beyond the listing step.

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