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

With no annotations provided, the description carries the full burden. It discloses key behaviors: 'Returns an unsubscribe URL' and 'Multiple monitors per email allowed, one per domain.' However, it does not mention alert frequency, error handling, or the exact response format, leaving some behavioral aspects opaque.

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 three sentences, each earning its place: purpose, use case, and return value/constraints. It is front-loaded with the primary purpose and contains no redundant information.

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 simple 2-param tool with no output schema and no annotations, the description is fairly complete. It covers what the tool does, when to use it, the return value (unsubscribe URL), and constraints (multiple monitors per email, one per domain). Missing details like response structure and error cases are minor for this simplicity.

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 input schema already covers both parameters with descriptions, so schema coverage is 100%. The description adds context that domain 'no scheme, e.g. 'stripe.com'' and clarifies the relationship between email and domain, but this is supplementary rather than essential.

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 clearly states the tool's purpose: 'Register an email to get alerted when the indicated domain's agentic readiness score drops.' It uses a specific verb (register) and resource (email), and distinguishes itself from sibling read-only tools by focusing on alerting/monitoring.

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?

The description provides a clear use case: 'Useful for agents tracking a dependency's agent-readiness health — e.g. an agent that relies on stripe.com's MCP surface wants to know the moment it regresses.' It does not explicitly name alternative tools, but the context strongly implies when to use it versus read-only tools like get_site_details or check_url.

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