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

The annotations already signal readOnlyHint=false and destructiveHint=true, but the description adds meaningful behavioral context: the call may incur charges under the bound API Token's pricing and budget. It also clarifies that exactly one call is made, which is useful given openWorldHint=true. No contradiction with annotations exists.

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 compact and front-loaded: the main action is stated first, followed by the charge warning, then the parameter naming guideline. Every sentence earns its place with no filler or redundant restatement of the tool name.

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 dynamic endpoint-calling tool, the description covers the essential operational concerns: validation, single-call behavior, charge risk, and parameter source. The output schema exists, so return-value details are not required here. The reference to get_endpoint_schema fills the main knowledge gap for constructing valid calls.

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 0%, so the description must compensate. It does so by explaining that params should use snake_case names from get_endpoint_schema, directly addressing the opaque 'params' object. This is essential guidance for an otherwise undocumented parameter structure.

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-resource pair: 'make one JustOneAPI endpoint call by endpoint_id.' It clearly distinguishes call_endpoint from the sibling tools (search_endpoints, get_endpoint_schema, get_account_balance, etc.) by stating the action is an actual endpoint invocation.

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 clear context for when to use this tool: when you need to execute an endpoint call. It also gives an important usage prerequisite: 'Params should use snake_case names from get_endpoint_schema,' which routes the agent to a sibling tool for parameter discovery. It does not explicitly list when-not-to-use scenarios, but the context is strong.

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