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

Adds real behavioral context beyond the readOnly/idempotent/closed-world annotations: the API key is read from SIGNUPBOUNCER_API_KEY, the call has a 1.5-second limit, and any failure fails open so the signup proceeds. These are exactly the operational facts an agent needs and cannot infer from annotations.

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?

Three sentences, front-loaded with the return value, then usage trigger, then runtime constraints. The stack enumeration is long but earns its place because the list is the tool's core coverage contract.

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?

An output schema exists, so return shape need not be explained. The description still covers which stacks are supported, when to invoke it, and the timeout/fail-open behavior, leaving no meaningful gap for a single-enum-parameter tool.

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% with an enum, so the baseline is 3; the description goes further by noting that supabase and ory need no code (hook-based) while the remaining stacks are code samples. It adds per-option semantics beyond the bare enum list, though not full detail for each stack.

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 ('Returns the steps and the copy-paste code that checks new signups') and enumerates the exact stacks covered, so the agent knows precisely what artifact comes back. It is inherently distinguishable from the sibling check_email/explain_reason tools, which evaluate emails rather than emit integration code.

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 a clear trigger condition: 'Use it when the user is building or changing a signup, register or auth flow.' That is strong positive guidance, but it names no alternative or exclusion (e.g., using check_email for a one-off email check), so routing is left partly to inference.

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