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

Annotations declare readOnlyHint=false, non-idempotent and openWorld, so the agent knows this mutates external state; the description adds value beyond that by clarifying the mutation is only a short-lived login challenge, cannot move funds, and requires caller approval. That directly defuses the risk implied by readOnlyHint=false and destructiveHint=false. It does not state challenge TTL or replay characteristics.

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 sentences, no filler, and the core action plus its safety profile are front-loaded before the approval caveat. Every clause earns its place.

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-output-schema auth trigger, the description covers the action, the safety profile, and the consent requirement well. The remaining gap is the undocumented source_wallet parameter and the absence of any statement about what the challenge response contains or how it feeds into finish_wallet_auth.

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?

There is one required parameter (source_wallet) with 0% schema description coverage and only min/max length constraints, so the description carries the full documentation burden — yet it never mentions the parameter. The agent gets no hint that this is a base58 Solana public key, who the wallet belongs to, or whether it must match a session.

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 and resource: 'Create a non-transactional Solana signMessage challenge', and immediately scopes it as a short-lived login challenge, so the agent knows this is an auth-start operation rather than a transaction. It does not explicitly name the paired sibling finish_wallet_auth, so sibling routing rests on name similarity alone.

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?

Usage is implied: this is the entry point for a wallet login challenge, and 'Requires caller approval' signals the flow stops for user consent. However, there is no explicit when-to-use statement, no prerequisite (e.g. must be followed by finish_wallet_auth), and no exclusions relative to siblings like assetfare_create_session.

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