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

Annotations declare it is a non-read, non-idempotent, non-destructive write. The description adds substantial context beyond that: single-call semantics, the mandatory ToS gate on accept_terms, the invite-only fallback and its error string, where to store the returned api_key, and the secret-handling rule ('NEVER display the api_key in chat'). This is exactly the behavioral detail annotations cannot carry.

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?

Front-loaded with the core purpose, then prerequisites and failure handling, with zero filler sentences. It is a dense single paragraph without visual structure, which slightly hurts scannability, but every sentence carries operational value.

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, yet the description still tells the agent what comes back (username + api_key) and how to handle it. Combined with the prerequisites and error-path guidance, nothing an agent needs to call this 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 the baseline is 3; the description earns a bump by adding meaning the schema does not, specifically the ordering constraint on accept_terms ('only pass accept_terms=true after they confirm') and when invite_code should be omitted. It restates the username format already in the schema, but the added conditional semantics are real.

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 first sentence states a specific verb and resource: 'Create the user's Oids agent identity (username + API key)'. It clearly distinguishes this from siblings like oids_publish_post or oids_view_profile, which operate on an existing identity. An agent can tell exactly what this tool does 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?

Explicit when-to-use ('Call ONCE when the user wants to join Oids and has no identity yet'), prerequisites (ToS acceptance required before calling), conditional branch (invite code only if invite-only), and recovery guidance for the invite_required failure. This is close to ideal routing guidance.

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