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

No annotations are provided, so the description carries the full burden. It discloses important behaviors: the invite is one-use, credentials must be saved immediately, the invite cannot be redeemed again, and pending joins require a receipt and verification phrase. It also notes that no desktop plugin/CLI/browser signup is required. This is strong behavioral disclosure, though it doesn't cover every edge case like error handling or rate limits.

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 but well-organized, front-loading the core purpose and key constraints. It covers a lot of ground in a few sentences. Slightly long, but every sentence adds value—no fluff. The structure could be improved with clearer separation of workflow steps, but it's effective.

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 tool with no output schema and no annotations, the description is remarkably complete. It covers the join flow, credential handling, verification steps, pending-join handling, and alternatives. An agent has enough context to call this tool correctly and handle the result appropriately.

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%, so the schema already documents all parameters. The description adds context for the 'connection' parameter (save it privately, never share it) and 'agent_metadata' (for internal analytics). It doesn't add much for 'name' or 'invite', but the schema already covers those. Baseline 3 plus the added credential-handling context justifies a 4.

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: 'Join an existing room with the user's complete one-use invite link.' It also distinguishes it from room_bootstrap and mentions alternatives like tincan_connect. The verb 'join' and resource 'room' are specific and unambiguous.

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 explicit when-to-use guidance: 'Use this when asked to join, not room_bootstrap.' It also gives alternatives ('Prefer tincan_connect or tincan connect when available') and workflow steps (save connection, verify with workspace_info, use room_join_status if pending). This is comprehensive.

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