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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds genuinely new behavioral context: the return shape ('JSON:API data and relationships') and the underlying endpoint (GET /api/commercial_purchases_payments/{id}), which tells the agent what to expect back.

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?

Three short sentences, front-loaded with the core action and free of filler. The endpoint sentence is somewhat redundant with the name but is compact enough to earn its place for an API-mapping agent.

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 single-parameter read with no output schema, the description covers the operation, the id semantics, and the return envelope. Nothing essential is missing, though a note on error behavior for unknown ids would complete it.

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 0%, but with a single required parameter the burden is light. The description clarifies that id is a numeric record id, which adds a little meaning, but the regex pattern in the schema already enforces the numeric format and no further guidance (e.g. where ids come from) is given.

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 ('Read') and resource ('purchase payment') and scopes it to a single record by numeric id, which distinguishes it from the list_* siblings by implication. It does not explicitly name toconline_list_purchase_payments as the way to obtain ids, but the singular read 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 phrase 'by numeric record id' implies this is used after you already have an id, but the description never states when to prefer this over the list endpoint or how to get an id in the first place. 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.