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

Annotations already declare readOnly/idempotent/safe-read, so the bar is lower. The description adds value beyond that: downloadPath requires Bearer auth, public sharing is disallowed, paid-event materials only need a login, and needsReupload flags require organizer re-upload. It does not cover output shape or pagination, keeping it from a 5.

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?

Dense but front-loaded: what it returns first, then sibling routing, auth, and the needsReupload caveat. Each sentence carries distinct information, though the mixed CN/EN shorthand and packed clauses make it close to over-dense.

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 single-param read with 100% schema coverage and safety annotations, the description supplies the auth, sharing, unlock, and re-upload caveats an agent needs. No output schema exists, so return-shape explanation would help but the essentials for correct invocation are present.

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% and the single activityRef parameter is fully documented as slug-or-id with back-references to get_activity/get_signup_activity. The description adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 a specific verb and resource: list handouts/files/photos plus lockedCount for an activity, scoped by current permissions. It explicitly contrasts with list_my_activity_history's materialsCount (cross-activity aggregate), so the agent can distinguish it from a sibling.

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 concrete when/when-not routing: use materialsCount in list_my_activity_history for cross-event summary; for free unregistered events confirm then join_activity_online to unlock; for download use get_activity_material_download. Multiple alternatives are named with the condition that selects them.

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