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

Beyond the annotations, the description discloses required login, the 0-based ids ordering contract, the silent-ignore behavior for foreign ids, and the risk of sortOrder collisions when ids omit rows. None of this contradicts the readOnly/destructive/idempotent hints; it adds operational context the annotations do not carry.

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 organized into three labeled sections and uses compact bullet-style notes. Every sentence adds information — trigger, workflow, return shape, pitfalls, and sibling routing — with no 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?

Even without an output schema, the description states the return is the full re-ordered list and warns not to rely only on ok. Together with the annotations, it covers auth, prerequisites, ordering contract, silent filtering, and the alternative tool, so an agent has enough to invoke it 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?

With only 50% schema coverage, the description compensates by defining ids as the complete 0-based new ordering and warning that every material must be included. activityRef's meaning is already in the schema, and the description further ties it to the activity's material scope.

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 states a specific operation — reorder all materials for one activity — and the title/description align. It explicitly distinguishes this tool from update_activity_material ('这个工具只排序，改名字/可见性走 update_activity_material'), so an agent can separate it from close siblings.

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 an explicit trigger ('主办方要把某份讲义挪到最前面') and a combination chain: fetch with list_activity_materials, pass a complete new order, then inspect the returned full list. It also states what the tool does NOT do and routes name/visibility changes to update_activity_material.

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