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

Annotations already declare readOnlyHint=true, so the description doesn't need to repeat that. It adds value by enumerating the specific data categories the add-on unlocks, which helps the agent understand what information the tool can reveal about the account's capabilities. This is behavioral context beyond the annotations, though it doesn't describe the tool's own side effects or response format.

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 long sentence starting with the core action, followed by a list of offerings and then usage triggers. It's slightly verbose but each element is functional: the list informs the agent of possible query scope, and the triggers clarify invocation. No filler sentences.

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 the tool has no parameters and an output schema is present, the description covers all necessary aspects: what the tool does, when to use it, and what the add-on includes. The agent can confidently invoke it without missing context, and the output schema will handle return structure.

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 has zero parameters, so there is nothing to explain. A baseline of 4 is appropriate because the description correctly omits parameter details, and with 100% schema coverage and no params, there's no gap to fill.

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 uses a specific verb 'Check whether' and a clear resource 'Maritime Reports add-on', and states exactly what the tool confirms. It distinguishes itself from siblings by focusing on add-on status rather than data retrieval, which is implicit in the naming but made explicit by mentioning 'intel_*' tools.

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 explicit trigger conditions: when the user asks about add-on availability, when an intel_* tool indicates it's missing, or after a purchase/update. This is precise guidance that tells the agent exactly when to invoke this tool, and it even implicitly excludes other scenarios.

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