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

With no annotations provided, the description carries the transparency burden. It discloses the data provided (open, high, low, close, volume, metrics) and the 'end-of-day' timeframe, but does not discuss return format, rate limits, or any query restrictions beyond parameters.

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 two sentences: the first states the action, the second lists data content. It is efficient, though 'using the Detailed Historical Price Data API' adds minor redundancy and could be trimmed without loss.

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?

Given the tool's simplicity (3 params, no output schema, no annotations), the description adequately covers purpose and data fields. It lacks explicit return format details but is otherwise complete for a straightforward historical data retrieval tool.

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%, with each parameter (symbol, from, to) already described in the input schema. The description adds no new parameter semantics beyond saying 'stock indexes', so the baseline of 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?

The description clearly states the tool accesses full historical end-of-day prices for stock indexes, with a specific verb and resource. It distinguishes itself from sibling tools like getHistoricalIndexLightChart by using 'full' and listing detailed data fields.

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?

No explicit guidance is provided on when to use this tool versus alternatives. While it implies use for detailed index historical analysis, it does not mention exclusions or alternative tools, leaving the agent to infer from the name and data content.

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