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

With no annotations provided, the description carries the full burden, and it does meaningfully: it discloses that new users get registered, that the call produces a key, and that the operation is free. These side effects go beyond anything the schema states. It does not cover failure behavior (e.g., invalid join code), but the main behavioral consequences are transparent.

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 purpose is front-loaded in the first sentence, and each clause earns its place. The standalone 'Free.' sentence is terse but conveys a distinct cost signal. Nothing is wasted, though it could be slightly tighter as prose.

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?

Against moderate complexity (3 params, one nested object) with no annotations and no output schema, the description covers the action, trigger condition, side effects (registration, key issuance), and cost. The 'gives you a key' effectively hints at the return outcome. Missing are failure semantics and what the key is used for, but these are minor for a join 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 description coverage is 100%, so the baseline of 3 applies. The description and schema jointly reinforce that name and business are only used when the user is new, but the description adds no parameter-specific meaning beyond what the schema already conveys.

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 names a specific verb (join), resource (negotiation), and mechanism (join code sent by the inviting agent), which clearly separates it from siblings like negotiation_open (create) and negotiation_list (view). The conditional registration note further distinguishes it from agent_register.

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 gives clear context for when to use the tool: when another agent has invited you and sent a join code. It also implicitly addresses the alternative of separate registration by clarifying that new users are registered 'in the same call,' so no separate agent_register step is needed. It stops short of explicitly naming alternatives or exclusions.

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