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

Beyond the annotations it discloses the ≤30MB fetch-to-private-storage limit, automatic image moderation (机审), the publish side effect that SLIDES/FILE broadcast to registrants, and the default visibility split (PHOTO=PUBLIC, others=REGISTERED). These are exactly the side effects and constraints annotations cannot express.

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 single dense paragraph is front-loaded with the auth/role constraint and every clause carries information (limits, moderation, side effects, defaults, follow-ups). It is terse rather than padded, though the semicolon-packed style mixes several topics without visual grouping.

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 5-parameter upload tool with no output schema, the description covers auth, limits, defaults, side effects, and follow-up tools, which is close to complete. It does not say what the call returns (e.g., a material id needed for later update/remove), leaving a small gap.

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 100%, so the baseline is 3; however the description adds default-value semantics for visibility (PHOTO defaults to PUBLIC, other kinds to REGISTERED) that the schema does not encode. It also advises confirming 'name' and visibility before publishing, which gives the two enum fields operational meaning.

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 a specific verb and resource (upload one activity material by link) and scopes it to the organizer role with a login requirement. It also distinguishes itself from related siblings (list_activity_materials for verification, update_activity_material for rename/visibility), so an agent can route without opening any schema.

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 states the precondition (login + organizer), the size constraint with a fallback ('大文件用/pro'), and explicitly routes rename/visibility changes to update_activity_material and verification to list_activity_materials. The '/pro' alternative is left opaque, which slightly weakens otherwise strong routing guidance.

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