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

With no annotations, the description carries the full burden and does surface a genuinely important behavioral trait: this is a signature, not a transaction, with no fee and no asset movement. That reassures the agent about side effects. It omits other relevant behaviors such as message expiry, single-use semantics, or what the returned message contains.

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, front-loaded with the action and result, then the safety caveat, then the follow-up call. No filler or repetition.

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 single-parameter, no-annotation, no-output-schema tool, it explains both the input and the general nature of the return value ('the exact message to sign') and the chaining step. Only minor operational details (session lifetime, signed-message contents) are absent.

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 0% and the single parameter has no description, so the description must compensate; it establishes that the input is a Solana address, giving the parameter clear meaning. Length bounds (32-44 chars) are left to the schema, which is acceptable since the semantic role is covered.

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 concrete input-output contract ('Give a Solana address; get the exact message to sign'), which is a specific verb+resource rather than a restatement. It also names the sibling agent_session_verify as the next step, letting an agent distinguish the two endpoints without reading either 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?

Clearly positions this as the first step of the sign-in flow and tells the agent to follow with agent_session_verify using the base64 signature, which is actionable sequencing. It doesn't state any exclusions or when-not-to-use cases, so it stops short of 5.

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