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

With no annotations, the description carries the full behavioral burden. It discloses that the return is compact CSV and that params mirror the live call, but it omits read-only confirmation, auth/rate-limit requirements, pagination behavior, and error handling beyond what the schema's limit field implies.

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 are front-loaded with the purpose and then the parameter/return note. There is no filler, and the key information appears 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 description covers the tool's purpose and parameter relationship, but with no output schema it only says 'returns compact CSV' without explaining fields, columns, or the meaning of change points. For a five-parameter tool with a nested params object, that leaves a meaningful gap in return-value context.

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%, so the schema already documents all five parameters including the nested params object and default series behavior. The description adds little beyond restating that params match the live call, which is already present in the schema.

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 resource and scope: recorded history/change points for an endpoint, with examples like exchange rates and weather. It clearly contrasts with live data by saying it uses the same params as the live call, but it does not explicitly name call_api as the sibling to use for live data.

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 only usage guidance is 'Use the same params as the live call,' which implies this tool is for historical data but does not state when to use it instead of call_api or search_apis. No exclusions or alternatives are given.

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