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

Beyond the annotations (readOnlyHint=false, openWorldHint=true, idempotentHint=false), the description discloses the one-time-return semantics of the key, that it must be saved securely, and that the MCP session may already be authenticated via the connection_authenticated response field. That is meaningful operational context an agent cannot get from the schema.

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?

It is front-loaded with the core action and keeps the branching logic compact, with every clause carrying actionable meaning. The final OAuth sentence is slightly long but earns its place by preventing unnecessary calls.

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 no output schema and no parameters, the description must carry the full interaction flow, and it does: creation, one-time capture, session-auth detection, reconnect instructions, and the OAuth bypass path. Nothing needed to call this tool 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?

The tool takes zero parameters and the description explicitly confirms 'No arguments,' which removes ambiguity about invocation. There is no parameter-level detail to add, so the baseline for a zero-param tool applies.

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 opens with a specific verb and resource: 'Create a zero-credit API key, returned once, and save it securely.' It also names the follow-on sibling (create_credit_checkout), so an agent can place this tool in the workflow without consulting other schemas.

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 gives explicit branching guidance: use create_credit_checkout when connection_authenticated is returned, otherwise configure Bearer auth and reconnect. It also states a clear exclusion — OAuth-capable clients should skip this tool because Connect is prompted automatically.

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