fmp_key_metrics

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

No annotations are provided, so the description must carry the full burden of behavioral disclosure. It fails to mention that this is a read-only operation, whether any special permissions are needed, or what the response format looks like (e.g., returns historical metrics for a period). The description only lists metric types and one parameter behavior, leaving much behavioral ambiguity.

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 short and front-loads the metric list, but it includes a docstring-like 'Args:' section that is redundant with the input schema. While not overly verbose, the 'Args:' section adds little value and could be trimmed. The core description is concise enough but has minor non-essential structure.

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 has an output schema, the description need not explain return values in detail. However, with no annotations and low schema coverage, it should provide more context about the tool's scope (e.g., that it returns historical metrics for a given symbol, not just current values). The description is adequate for a simple metrics tool but lacks depth to be fully complete, such as noting that it returns time-series data or that 'ttm' is a special mode.

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 needs to compensate. It explains only the 'ttm' parameter ('Return trailing-twelve-month values instead of discrete periods'), which adds value beyond the schema. However, it omits details about 'period', 'limit', and 'symbol' meanings, which are inferable from their schema definitions but could benefit from clarification (e.g., 'limit' likely controls number of periods returned). Thus it partially compensates but not fully.

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 provides 'Per-share and valuation metrics' such as P/E, EV/EBITDA, ROIC, and FCF per share. This distinguishes it from sibling tools like fmp_ratios or fmp_enterprise_values, though not explicitly naming them, the focus on per-share and valuation metrics differentiates it sufficiently.

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 no guidance on when to use this tool versus alternatives. It does not mention any prerequisites, exclusions, or comparisons to sibling tools. The only usage hint is the ttm parameter for trailing-twelve-month values, which is a functional detail rather than usage guidance.

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