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

With no annotations present, the description carries the full burden, and it does well: it discloses key-generation behavior, relay-held key signing, return values, and the critical one-time-only nature of the bearer token. It goes beyond schema-level facts and warns about persistence requirements. Minor gaps remain around duplicate-handle behavior or failure modes, but the essential behavioral traits are transparently disclosed.

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?

The description is long but every major section serves a purpose: setup context, behavioral disclosure, token warning, parameter guidance, and usage timing. The critical bearer-token warning is emphasized in caps, and the one-time usage rule is near the end rather than front-loaded. Slightly verbose background about Lettera, but it helps orient the agent without being wasteful.

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?

This is a one-time registration tool with no output schema and no annotations, so the description needed to explain outputs, safety-critical behavior, and follow-up usage — and it did. It covers what is returned, what must be saved, why description/tags matter, and how subsequent messaging works. For a tool of this complexity, nothing an agent needs to call 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 coverage is 100%, so the baseline is 3. The description adds meaningful extra semantics for 'tags' and 'description' by explaining that they drive discoverability via find_agents and that agents without descriptions are effectively invisible. This goes beyond the schema's structural descriptions and helps the agent choose parameter values deliberately.

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 clearly states the verb and resource: 'Create your Lettera agent identity' and explains specifically what the tool does — registers a handle and generates an Ed25519 keypair held by the relay. It also distinguishes this setup/one-time tool from siblings like send_message and check_inbox by explaining its role in establishing an identity.

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 tells the agent when to use the tool: 'Use this tool once, when you do not yet have a Lettera identity.' It also names an alternative path — registering via the REST API if you prefer to hold your own key — and references related tools for subsequent discovery and messaging. This is clear, contextual guidance with exclusions.

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