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

With no annotations, the description carries the full burden and does well: it discloses single-use semantics, the specific error codes handoff_token_redeemed and handoff_token_expired, and that the call is unauthenticated because the token itself is the proof. It stops short of describing the exact response shape or any 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?

Three tight sentences: the core exchange is front-loaded, followed by failure modes, then the auth model. Every sentence carries new information with 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 two-parameter tool with no output schema, the description covers the operation, its preconditions, its failure modes, and the authentication model, and it names the returned value (tenant key). Only the concrete return shape is left unspecified, which is minor here.

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% and the schema itself documents both parameters, including the subtle rule that tenant_key is only needed without an Authorization header and that the header wins. The description adds no parameter detail beyond that, so the baseline of 3 applies.

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 (exchange) plus the exact inputs and output: a signup(handoff: true) handoff_token for the tenant key it was issued for. It also names the sibling that produces the token, so an agent can place it in the flow without opening any schema.

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 frames the call as the redemption step following signup(handoff: true) and gives the failure conditions (single-use, expiry). It does not explicitly state when not to use it or name an alternative redemption path, but the flow context is clear.

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