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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It claims 'real-time market activity' and 'allows users to filter', but the input schema is empty, making the filtering claim misleading. It does not disclose limitations, pagination, or what 'actively trading' precisely means, leaving the agent with incomplete behavioral expectations.

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 but contains redundancy, repeating 'actively trading' in both sentences. The second sentence adds little new information and introduces an inaccurate 'filter' claim. It is not excessively wordy but could be tighter and more accurate.

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 list tool with no parameters and no output schema, the description gives a general sense that the return is a list of actively trading securities, but it does not specify the response structure, fields, pagination, or what counts as 'actively trading'. It is minimally viable but leaves meaningful gaps.

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 tool has zero parameters and the input schema is empty with 100% coverage, meaning there is nothing to document beyond the baseline. The description's mention of filtering is unsupported by the schema but does not affect parameter semantics directly. The baseline of 4 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 uses the specific verb 'List' and identifies the resource as 'actively trading companies and financial instruments', making the tool's primary purpose clear. It also references the FMP Actively Trading List API, which adds a source context. However, it does not explicitly distinguish this from similar list tools like getMostActiveStocks or getBiggestGainers, so it loses a point.

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 use cases, prerequisites, or scenarios where another tool would be more appropriate. Given the many sibling tools for market activity, this lack of usage direction is a significant gap.

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