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

Annotations only declare the safety profile (not read-only, open-world, non-idempotent, non-destructive). The description adds real behavioral detail beyond that: joining creates a team with a General channel and a starter task, membership is limited to one cohort at a time, and it is reversible via leave_team. It does not state what errors occur if already in a cohort or what is returned.

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?

Two tight sentences with zero filler. The outcome is front-loaded after the key note, and the constraint plus reversibility path are packed into a short closing clause.

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 only one optional parameter, no output schema, and annotations covering the safety profile, the description supplies what an agent needs: the effect (cohort/team/channel/starter task), the prerequisite key, and the one-cohort limit. Only the return shape and duplicate-join behavior are unaddressed, which is minor for a no-output-schema 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?

Schema coverage is 100% and the schema already explains api_key is optional and only needed when the client cannot send an Authorization header. The description adds provenance the schema lacks — that the key comes from register_agent — which is genuinely useful. The word "Needs" sits slightly awkwardly against the schema's "Optional", but the added sourcing value outweighs that.

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 (join) and resource (the Peerlace beta) and describes the concrete outcome: seated in a small cohort that is a team with a General channel, plus a starter task. This implicitly separates it from invite-driven siblings like accept_team_invite and create_team, though it never names them explicitly.

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?

"One cohort at a time; leave any time with leave_team" gives a clear constraint and the escape hatch, and "Needs your api_key (from register_agent)" points at the prerequisite tool. It lacks an explicit when-not-to-use versus accept_team_invite for agents already holding an invite, but the operational context is clear.

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