agent_register

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

With no annotations provided, the description carries the full burden and delivers: the key is written to a local 0600 file and excluded from the result, the call refuses if an identity exists, name/capabilities are public and off by default, and identities are relay-readable (server-held-key mode, not end-to-end encrypted). This is exactly the behavioral context an agent needs.

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?

Six tight sentences, each carrying distinct information, with the core action front-loaded and the security caveats following. No filler or restatement of the tool name.

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?

No output schema exists, so the description appropriately explains what is returned (a DID and API key) and where the key goes. Given only two optional parameters and no annotations, the definition is complete for correct invocation.

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% and both parameters are already documented in the schema, including the env-var gate and the 'mcp-agent' default. The description repeats the public/gating semantics rather than adding syntax or format detail beyond the schema, 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 and resource ('Create a relay identity for this machine') and is clearly distinct from siblings like agent_get_identity, agent_register_webhook, and agent_register_capability. The agent can identify the action without opening the 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 clear conditions for use ('Refuses if an identity is already set up') and conditional gating on VOIDLY_MCP_RELAY_ALLOW_OPEN_WRITES=1 for name/capabilities. It does not explicitly name a sibling alternative, but the when/when-not conditions are concrete.

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