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

With no annotations, the description carries the full burden, and it does so well: it says the tool has no parameters, is free, is not the subscription mechanism, and offers no recommendation or probability of default. It also discloses watcher categories and delivery mechanics, giving the agent a realistic model of the service without overstating side effects.

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 information-dense and front-loaded with its purpose, but it is a single long run-on passage that would be easier for an agent to parse as structured bullets. Every clause adds content, so it is not padded, but the structure is not ideal.

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?

Given no output schema, the description covers the key contents an agent needs: what is monitored, delivery mechanism, plan limits, capacity constraints, consumer-use restrictions, limitations, and the subscription endpoint. The phrase 'and the endpoints' is slightly vague, but enough is included to make the tool usable.

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?

There are no parameters, so the schema leaves nothing to document; the description explicitly confirms 'No params.' This matches the baseline for a zero-parameter tool and adds no confusing parameter information.

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 action and resource: 'Describe XRPLHub's continuous-monitoring service' and immediately states the decision it supports. It also distinguishes itself from the subscription endpoint by saying 'Subscribing needs an API key over HTTP (POST /api/monitor/subscribe), not this tool.'

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 clear context for when this information is relevant ('so an agent can decide whether to use it') and explicitly routes subscription actions away from the tool to the HTTP endpoint. It clarifies the service is advisory only ('never a replacement; no recommendation, no probability of default'), though it does not name sibling tools as alternatives.

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