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

Annotations cover safety (readOnly false, destructive false, non-idempotent), and the description adds real context beyond them: single-use semantics, default 1 use / 24h validity, and the fact that the code is relayable by a human without exposing a key. It does not discuss revocation, reuse-after-max_uses behavior, or what happens if the same key mints repeatedly.

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?

Three tight sentences: the action and its counterpart sibling come first, then the security rationale, then key scoping and defaults. No filler, no restated title, and the most decision-relevant fact (code vs key) is front-loaded.

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?

An output schema exists, so return details (expires_at echo) need not be described, and the schema already bounds ttl_s and max_uses. What remains thin is error/edge guidance and explicit negative routing against the other bus_* minting siblings.

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 already 100%, so the baseline is 3; the description nevertheless adds meaning by explaining that a bus key silently scopes the invite to its own project while an owner key must name it. The 'Default 1 use, 24h' phrase merely restates the schema defaults, adding no new information.

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?

Names a specific verb (mint) and resource (one-time INVITE CODE) and immediately ties it to the counterpart sibling bus_join, so an agent can distinguish inviting from joining. It also draws the boundary against key-minting by stating 'a code is not a key.'

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?

Explains the condition that selects this tool (a new teammate needs to join by itself) and points to bus_join as the receiving side. It also gives the key-type rule for who supplies project, but never explicitly says when NOT to use it (e.g., use bus_mint for a durable key instead).

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