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

With no annotations, the description carries the full behavioral burden: it does disclose token lifetime (30 days), revocation ('revocable from the account page'), the base64 Ed25519 signature requirement, and the exactness constraint on the message, which are meaningful traits. It stops short of stating the side effect (creating a session), what happens on signature/address mismatch, or any rate/permission constraints, leaving notable gaps for an auth-mutating tool.

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?

Two compact sentences with the required inputs front-loaded ahead of the return value, and no padding. The opening is a verbless fragment, which slightly reduces readability, but nothing is wasted.

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?

There is no output schema, so the description correctly describes the return value (a session token to pass as `session`), plus its lifetime and revocability — the essentials for an agent to proceed. It omits failure behavior and the precise meaning of `address`, but for a three-parameter step in a known sequence it is largely sufficient.

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 0%, so the description must compensate, and it does document the meaning of all three parameters: the message provenance ('exact message from agent_session_start') and the signature encoding ('base64 Ed25519'). The 'address' parameter is named but not explained (presumably the wallet address), and no format/length constraints from the schema are echoed, so it stops just short of full coverage.

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 title supplies the verb ('Finish the wallet sign-in') and the body confirms the outcome ('Returns a session token'), and it explicitly distinguishes itself from agent_session_start, whose message output it consumes. The body sentence itself is a noun-phrase list of inputs rather than a stated verb+resource, so an agent must lean on the title for the action, but the combined definition is unambiguous.

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 implies the correct sequence by requiring 'the exact message from agent_session_start' and by telling the agent to pass the returned token to 'every later call', which is genuine workflow guidance. However, it never states when this tool should not be used, what to do if the message is missing/expired, or any alternative path, so usage is implied rather than explicit.

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