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

Beyond the annotations (which only assert non-read-only, non-idempotent, open-world), the description discloses the server-side validation chain, the 30-minute grant duration, single-use/replay protection, and a precise error taxonomy. This is exactly the behavioral context annotations cannot carry.

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 compact sentences, action front-loaded, with a trailing error list that is genuinely useful for handling failures. No filler or restatement of the tool name.

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 mutating authorization call with no output schema, the description covers inputs, validation, lifetime, and errors. It leaves the Solana `transaction` path and the exact success payload to the schema, a minor gap rather than a blocker.

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?

At 57% schema coverage, the description usefully clarifies what the signature must be *over* (the exact challenge, that receiver, that chain) and ties nonce/message back to destination_challenge. It stops short of explaining the Solana-only `transaction` alternative or the wallet/chainId fields, which the schema covers.

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 gives a specific action (hand over the signature from destination_challenge) and the resulting effect (builds may deliver to that receiver for 30 minutes). It clearly distinguishes itself from the sibling destination_challenge, which produces the challenge this tool consumes.

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 makes the prerequisite explicit (you must first call destination_challenge to get nonce/message) and states the outcome window, giving clear context for when to call it. It does not state any when-not-to-call condition or name an alternative path, so 4 rather than 5.

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