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

Beyond the annotations, it discloses the failure mode (a 409 that carries the real current state), the nonce-based replay behavior returning `repeated: true`, and that no credentials are required. `idempotentHint: false` remains consistent because a same-nonce replay returns a distinguishable response rather than a plain repeat. It omits the shape of a successful response beyond the transition name.

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?

Four tight sentences with the core action front-loaded and preconditions before error behavior. The closing line about no API key or sign-up is slightly promotional, though it does convey the auth requirement.

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 mutation tool with full annotation coverage, full schema coverage, and no output schema, this covers preconditions, conflicts, and retry semantics well. The remaining gap is that the set of allowed transitions and the success payload are never described, so an agent learns the state machine only by hitting errors.

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 baseline is 3, and the description earns above that by explaining the coupling between `from`, the allowed-transition check, and the 409 payload, plus how `nonce` interacts with replays. That adds real meaning not present in the one-line schema descriptions.

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 opens with a specific verb and resource ("Move a handoff to the state named in to") and frames the operation as an optimistic-concurrency state transition, which is clearly distinct from create_agent_handoff or read_agent_handoff by nature. It never names a sibling tool explicitly, so it falls short of the top mark for differentiation.

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?

It defines the precondition for a valid call (the handoff must be exactly in `from` and the transition must be allowed) and describes the retry path, so usage is implied well enough to attempt a call. It never states when to prefer this over read_agent_handoff or how to discover the set of allowed transitions, which is the main practical gap.

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