join_circle

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

Annotations already cover mutation (readOnlyHint=false), idempotency, and non-destructiveness. The description adds meaningful behavioral context: the OPEN flag precondition, the failure mode, and the membership object returned. This goes beyond what the annotations alone 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 compact and well-structured, with the key precondition stated up front and clear Args/Returns sections. Every sentence adds useful information; there is no filler.

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-parameter tool, this is complete: precondition, alternative usage, error behavior, actor, and return shape are all present. The output schema exists, and the description even summarizes the returned membership fields, so no critical calling context is missing.

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 description coverage is 0%, so the description needed to compensate for the undocumented parameter. It only restates what the schema already conveys (circle_id is a string id) and adds no guidance on format, source, or validation.

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 action (join), a specific resource (circle), and a clear actor (current user). It also distinguishes itself from add_circle_member, so an agent can tell which tool fits without opening schemas.

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?

Explicitly says the circle must have the OPEN config flag (16) and warns that otherwise the server errors. It also names add_circle_member as the correct tool for invitation-only circles, giving clear when-to-use and when-not-to-use guidance.

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