mailkite_register

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

Description discloses behavior well beyond annotations: immediate API key return, verification email, blocked sending until verified, 409 on existing email, and session-token requirement. Annotations only provide readOnlyHint/idempotentHint/destructiveHint (all false), so the description carries full behavioral disclosure and does so comprehensively.

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 description is a single focused paragraph with three sentences. It front-loads the core purpose, then adds return/verification details, then error behavior and use case. All sentences earn their place; only minor trimming (e.g., 'Powers plugin/CLI onboarding' could be omitted) but structure is strong.

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?

For a registration tool with no output schema, the description fully covers what an agent needs: what it returns (API key), verification flow, error for existing email, requirement for session token, and mentions polling helper. There are no missing call-time details that would leave an agent unsure how to invoke or interpret results.

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% and each parameter (email, ref, channel, referrer) already has a descriptive explanation. The description adds no new param-level meaning beyond what schema provides (e.g., it doesn't clarify the format of ref or channel further). It's adequate but not additive beyond the schema's already good descriptions.

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 action (create account), the resource (MailKite), and key characteristics (no password, returns API key). It clearly distinguishes from siblings like mailkite_get_api_key or mailkite_rotate_api_key by focusing on account creation. The 409 existing-email case adds precision.

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?

Mentions 'Powers plugin/CLI onboarding' which gives a plausible use case, and the requirements (management session token) are clear. It doesn't explicitly list alternatives or when-not-to-use, but the uniqueness of account creation among siblings makes the context clear enough.

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