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

Annotations already declare readOnlyHint=true, so the safe-read nature is covered. The description adds useful detail about the data (actual vs. estimated EPS) but does not disclose additional behavioral traits like response format, pagination, or any limitations. It does not contradict the annotations.

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 a single concise sentence that front-loads the core purpose and includes the REST endpoint for reference. Every word earns its place with no redundancy.

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 simple read-only tool with only two parameters and full schema coverage, the description provides sufficient context: it names the data type, the comparison, and the period granularity. It does not describe the return structure, but given the low complexity and no output schema, this is a minor gap.

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 parameters symbol and limit are already well-documented in the schema. The description adds no additional parameter semantics beyond what the schema provides, which matches the baseline for high schema coverage.

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 identifies the tool as providing historical quarterly EPS surprises, specifically actual vs. estimated EPS by period. It names the underlying Finnhub REST endpoint, and the 'historical' qualifier distinguishes it from sibling tools like finnhub_earnings_calendar.

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?

Usage context is implied by 'Historical quarterly' and 'by period', suggesting it is for past earnings surprise data rather than future earnings dates. However, there is no explicit guidance on when to prefer this tool over alternatives such as finnhub_earnings_calendar or finnhub_basic_financials.

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