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

Annotations already declare readOnlyHint=true, so safety is covered by structured data. The description adds the underlying endpoint (GET /fees) and the optional-filter nature, but says nothing about pagination behavior, result ordering, or volume/rate considerations for a list endpoint.

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?

Two short sentences, front-loaded with purpose and followed by the filtering scope; the endpoint reference is a minor but useful addition. Nothing is wasted, though it is close to the minimum viable length.

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 five-parameter, zero-required list tool with a fully documented schema and no output schema, the description covers purpose and filters adequately. It is thin on pagination semantics and does not explain what a fee record contains, which an agent may need for follow-up reasoning.

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 all five parameters are individually documented in the schema, so baseline is 3. The description echoes the filter dimensions (customer/subscription/fee type) but adds no syntax, format, or default detail beyond what the schema already provides.

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+resource ('List fees') and enumerates the filterable dimensions (customer, subscription, fee type), so the agent knows exactly what the tool returns. It does not explicitly differentiate itself from other list_* siblings, but the resource name 'fees' is unambiguous.

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 word 'optionally filtered by' implies a valid usage context, and the API endpoint gives orientation, but there is no explicit when-to-use guidance, no prerequisites, and no mention of alternatives such as a per-invoice or per-subscription fee endpoint.

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