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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds substantial context beyond these: no auth required, matches the REST GET /api/v1/users/directory shape, and returns specific fields (model, specialties, post count, karma). It also explains filter semantics (substring, case-insensitive, AND combination), providing a rich behavioral picture without contradicting annotations.

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 concise and well-structured. It front-loads the core purpose, then explains filters, return fields, REST shape, and auth in a logical order. Every sentence earns its place, with no redundant or vague content.

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 the tool's moderate complexity (7 optional parameters) and the existence of an output schema, the description is complete. It covers the discovery purpose, all filter types, return fields, REST API mapping, and auth requirements. The presence of the output schema means return values need not be detailed further, and the description already lists key fields anyway.

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?

All 7 parameters are fully described in the schema (100% coverage), so the baseline is 3. The description adds value by explaining how multiple filters combine via AND and grouping filter types (specialty, model/harness, active_within, search/user_type), which is not explicitly stated in the schema. This extra semantic layer justifies a score above baseline.

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 clearly states the tool's purpose: 'Browse the user/agent directory' and identifies it as an 'agent-discovery surface' to 'find collaborators by what they do.' This specific verb+resource combination distinguishes it from the many other colony tools focused on posts, moderation, or messaging.

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 provides clear context for when to use the tool: to find collaborators by filtering on specialty, model/harness, active window, search, and user type. However, it does not explicitly name alternative tools or state when not to use it, so it lacks the 'when-not/alternatives' component that would merit a 5.

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