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

Annotations already establish read-only and idempotent behavior. The description adds substantial behavioral context by enumerating the exact fields returned (description, provider, sessions, prices, capacity, etc.) and disclosing that registration/payment happen externally via the share_url. This goes well beyond what annotations provide.

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 a single, well-structured sentence that leads with the action and resource, then provides a detailed list of return contents. Every listed item adds value and the length is justified by the tool's rich output. No fluff.

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 must explain return values, and it does so comprehensively for both activity-level and session-level details, including the external registration flow. The single parameter is fully documented via the schema, making the description complete for this tool.

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 schema covers 100% of parameters and already describes slug as the URL slug returned by search_activities. The description only repeats 'identified by its slug' without adding new meaning. Since schema coverage is high, the baseline of 3 is appropriate.

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 uses a specific verb ('Returns') and resource ('full details for one enrichment activity') with a clear identifier ('slug'). It distinguishes itself from siblings like search_activities (which lists activities) and get_provider_info (which gets provider info) by focusing on detailed per-activity retrieval.

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?

The description implies a workflow: the slug is returned by search_activities, and this tool follows to retrieve full details. This gives clear context for when to use it. However, it doesn't explicitly name alternatives or state when not to use it, so it falls just short of a 5.

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