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

Beyond the annotations, it discloses the passwordless model, that registering auto-emails a 6-digit code, that signup doubles as signin-start, the HTTP 400 + errors-array failure format, and that no prop_id is needed. These are behaviors an agent cannot infer from readOnlyHint/openWorldHint alone.

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 stage label and endpoint are front-loaded and every sentence carries routing or behavioral information. It is slightly dense with parenthetical asides, but there is 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?

With an output schema present, return values need not be explained. The description supplies the account-flow context, follow-up tool, error handling, and required inputs, so an agent has everything needed to call it correctly.

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 schema already documents all seven properties. The description only reinforces that firstname and phone are required and that prop_id is unnecessary; it adds little on is_owner, sms_unsubscribe, or the optional fields. Baseline 3 is appropriate.

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 names a specific verb and resource ("register a new beycome user") and even cites the endpoint (POST /auth/register), plus a lifecycle stage ("Account stage"). It is clearly distinguishable from the signin siblings it names.

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?

It states the trigger ("Use when the owner has no account yet"), the next step (beycome_signin_verify with the emailed code), an explicit exclusion ("do NOT call beycome_signin_start after signup"), and edge-case behavior (already-registered still sends a code). Nothing is left to inference.

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