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

Annotations already declare readOnly, idempotent, non-destructive, so the safety profile is covered. The description adds genuine value by disclosing what the response contains (fees, refunds total, settlement transfer state, chargeback flag) and mapping it to the REST endpoint — useful behavioral context beyond the annotations.

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 tight fragments: the payload summary front-loaded, endpoint last. Every clause earns its place with zero filler.

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 one-parameter read tool with no output schema, the description supplies the missing return-value picture and the endpoint mapping. It's essentially complete for correct invocation, with only sibling routing left implicit.

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 coverage is 100% with a single required charge_token and an example value, so the schema carries the parameter semantics. The description only echoes the ch_... token form, adding no syntax beyond what the schema already documents; baseline 3 is appropriate.

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 and resource ('One charge by token') and enumerates the notable fields returned, plus the underlying GET /charges/{token} endpoint. This distinguishes it from list_charges and search_charges by emphasizing single-charge retrieval, though it doesn't name those siblings explicitly.

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?

'One charge by token' implies retrieval of a single record versus the list/search siblings, but there is no explicit statement of when to prefer this tool or what prerequisite (a known ch_... token) selects it. Usage is inferable rather than stated.

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