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

Far exceeds the annotations (readOnlyHint=false, destructiveHint=false, openWorldHint=true). It discloses that codes are dual-channel (email + SMS), valid 30 minutes, that re-running invalidates the previous code, explicit rate limits (5/min, 100/day), and the non-obvious fact that auth failures still return 2xx so the body envelope must be read instead of the status.

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 operation, then structured into response-case bullets and constraints. It is long, but nearly every sentence carries distinct operational value (error branches, rate limits, code lifetime), so only minor trimming is possible.

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?

Even though an output schema exists, the description supplies the response-interpretation rules the schema cannot convey (ok mirrors HTTP status, check data.success, 422 masked-primary hint). For a passwordless auth entry point with tricky 2xx-on-failure behavior, 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 description coverage is 100% for the single 'email' parameter, so the schema already documents it and the baseline of 3 applies. The description adds workflow context around the email (what happens if no account matches, or if it hits a secondary address) but no new syntax or format meaning for the parameter itself.

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+resource ('send a one-time sign-in code') and immediately anchors it in the auth flow ('Account stage'), naming the sibling it pairs with (beycome_signin_verify) and the fallback (beycome_signup). An agent can distinguish it from every other sibling without opening a 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 explicit routing rules: run beycome_signup when 'Email not found.', exchange the code via beycome_signin_verify, and a hard 'never call it in a loop or as an automatic retry' exclusion. Both when-to-use and when-not-to-use are covered.

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