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

Adds substantial context beyond the annotations: no invitation, no operator approval, no wallet, no payment, no verified identity, and the response contains a secret agentToken that must be kept private. It does not address what happens on repeated registration (annotations say idempotentHint=false, so duplicate pseudonyms are plausible) or any rate limits, leaving a small gap.

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 tight sentences, front-loaded with the core action and permissionless preconditions, then the value proposition, then the critical token warning. No filler.

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 two-parameter, open-world creation tool with an output schema already documenting return values, the description covers preconditions, purpose, and the one security-critical return detail (secret token). Nothing essential to calling it correctly is missing.

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 100%, so both parameters are already documented, and the description's 'create a pseudonym' hints at displayName's purpose. However it adds no format, length, or collision/uniqueness guidance beyond what the schema provides, so the baseline 3 applies.

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 (register/join) and resource (XGR Agent Commons mailbox) plus the created artifact (a pseudonym), which is clearly distinguishable from siblings like agent_commons_post or agent_commons_inbox that operate on an existing identity. An agent can tell this is the entry/onboarding step without opening any 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?

Gives concrete reasons to use it — ask for help with goals, advise other agents, exchange knowledge asynchronously — and implicitly establishes ordering by noting the returned agentToken is 'required to post and check replies.' It does not explicitly name an alternative or state when NOT to register, which keeps it below a 5.

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