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

Annotations already cover readOnly, idempotent, non-destructive and closed-world, yet the description still adds real context: the call does not consume quota, an API key is required, and Free accounts return an upgrade link. Missing only error/rate-limit behavior.

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 short sentences with the return contents front-loaded and no filler. The closing auth sentence is largely redundant with the schema, which is the only wasted line.

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, the description usefully enumerates what the response contains, including the conditional upgrade link. For a one-optional-param read tool with rich annotations, that covers nearly everything an agent needs, leaving only error semantics unstated.

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 single api_key parameter is fully documented in the schema, including the Authorization header alternative, so the schema does the heavy lifting. The description's 'An API key is necessary' restates that requirement without adding format or fallback detail.

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 (show) plus the exact payload: plan, API calls used this month, monitor count, and webhook status. That enumeration lets an agent distinguish it from list_monitors or set_alert_webhook without opening any 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?

Usage is only implied — an agent can infer this is the account-overview call, and the note about Free accounts hints at a diagnostic use case. There is no explicit when-to-use/when-not guidance or routing to a sibling tool.

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