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

Annotations already disclose that this is a read-only, idempotent, non-destructive operation, so the safety profile is covered. The description adds only that results are heuristic ('look like subscriptions') but does not explain the detection criteria, false-positive behavior, return shape, or limitations, leaving meaningful behavioral gaps.

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 front-loaded sentence with no wasted text. Its brevity is appropriate and the key resource and behavior are placed immediately.

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?

The tool has no output schema, so the description would need to clarify return values or result shape, but it does not. It also omits routing guidance versus siblings and leaves the meaning of 'look like subscriptions' unspecified, which is a significant gap for a heuristic detection tool.

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 description coverage is 100%, and the single min_recurrence parameter is fully documented with a default in the schema. The description adds no additional parameter semantics beyond what the schema already provides, matching the baseline for high schema coverage.

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 states a specific verb and resource: 'Find recurring transactions that look like subscriptions.' It clearly identifies the tool as a heuristic subscription detector, though it does not explicitly differentiate itself from siblings such as find_anomalies, list_transactions, or search_transactions.

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 gives no explicit guidance about when to use this tool versus alternatives, nor does it state when not to use it. The phrase 'look like subscriptions' implies a detection use case, but the agent must infer routing from tool names alone.

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