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

With no annotations provided, the description must disclose behavioral traits itself. It mentions returned fields (date, price, volume) but fails to explain what 'light' means relative to the full chart, nor does it address output structure, limitations, or authentication. This is a significant gap for a read tool with an unspecified return format.

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 concise at two sentences and front-loads the main action. The phrase 'using the Historical Price Data API' is somewhat redundant and adds little value, but the overall length is appropriate and structured effectively.

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 tool with no annotations, no output schema, and a sibling that likely differs only in data granularity, the description is incomplete. It fails to clarify what differentiates 'light' from 'full', and does not describe the response shape or pagination, leaving an agent uncertain about the tool's practical behavior.

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?

The input schema provides 100% coverage with clear descriptions for all three parameters (symbol, from, to). The tool description adds no additional parameter-level meaning beyond what the schema already documents, 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 retrieves end-of-day historical prices for stock indexes, naming the resource and data fields. However, it does not distinguish itself from the sibling getHistoricalIndexFullChart, so it misses the top score for sibling differentiation.

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?

There is no explicit guidance on when to use this tool versus alternatives like getHistoricalIndexFullChart or intraday index chart tools. The description only implies a use case for end-of-day analysis, offering no exclusions or alternative suggestions.

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