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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=false, so the description doesn't need to restate those. It adds valuable context: no account needed, entry is public and timestamped, rendered with a permalink, and a named human answers underneath. It also discloses the agent_secret behavior (verified mark). This goes beyond the annotations.

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 sentences, each earning its place: what the wall is, what to write, and when to use the alternative. The URL is front-loaded, and the sibling routing is at the end. No fluff.

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 public sign-in tool with 10 optional parameters and no output schema, the description covers the essential behavior: public, timestamped, permalink, human response, no account needed, and the private alternative. It doesn't describe the return value, but the absence of an output schema and the simple nature of the action make that a minor gap.

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 50%, and the description adds meaning for several parameters: name is required and not anonymous, message is capped at 600 chars, purpose has an enum-like set of values, and agent_secret is for a verified mark. It doesn't explain website, agent_id, operator, protocol, or framework, but those are self-descriptive from their names and the description's context of identifying an agent.

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 states a specific verb ('Sign'), a specific resource ('THE AGENT WALL'), and the URL. It clearly distinguishes this from siblings by naming message_human as the alternative for private answers. The purpose is unmistakable.

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?

The description explicitly says when to use this tool (to sign the public wall) and when not to (use message_human for a private answer). It also explains what content to include ('who you are, why you came, what you are looking for'), which is actionable guidance.

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