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

The description goes far beyond the readOnlyHint annotation. It discloses pagination style (keyset), default sort, filter interactions (e.g., host alone forces identifier ordering, discovered participants lack name/card fields), and meta behavior (filter_count may return null on timeout). This adds critical behavioral context the annotation alone cannot 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 dense and comprehensive, but every sentence earns its place. It is front-loaded and well-structured. However, it could be slightly tighter (e.g., grouping some filter notes) to improve readability without losing detail.

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?

Given 19 parameters, no output schema, and only a readOnlyHint annotation, this description is remarkably complete. It covers pagination, sorting, all filter behaviors, special cases, meta details, and privacy constraints. There are no obvious gaps for an agent to use this 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?

With 100% schema coverage, the baseline is 3, but the description adds substantial value. For example, it explains the smart search logic for q, the special ordering constraints when host/doctype/transport_profile are used alone, and the role of each filter. This vastly exceeds the schema's parameter descriptions.

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 opens with 'List participants' and immediately clarifies the scope—'The participant set, keyset-paginated'—and enumerates sorting, filtering, and edge cases. This clearly distinguishes it from sibling tools like get_participant (single entity) or list_participant_events (events for a participant).

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 thoroughly explains the tool's behavior but never explicitly states when to use it versus alternatives (e.g., when to prefer get_participant or list_participant_events). Usage is implied through the feature set, but there is no 'when not to use' or direct comparison to siblings.

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