index_list_symbols

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 adds 'Updated overnight', informing about data freshness. However, it does not explicitly state that this is a read-only operation or describe any limitations, though for a list tool this is minimal risk. The 'FREE' label is more marketing than behavioral.

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 and front-loaded with the primary action. Every word earns its place, with 'Updated overnight' providing useful context without redundancy. It is appropriately sized for a tool with no parameters.

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 provides the essential information: what it returns and when data is updated. It might not describe the exact format of the symbol list, but for typical usage this is sufficient. The tool's simplicity means minimal additional context is needed.

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. According to the rubric, the baseline is 4 since there are no parameters to explain. The description does not need to elaborate on parameters, and the schema coverage is 100% vacuously.

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 states 'List all index symbols' with a specific verb and resource, clearly distinguishing it from sibling tools like stock_list_symbols and option_list_symbols by specifying 'index'. The prefix 'index' in the name reinforces this, making the purpose unambiguous.

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 makes clear that this tool is for listing index symbols, which is distinct from stock and option symbol listings. It does not explicitly mention when not to use it, but the sibling tool names provide context. For a simple list tool, the use case is unambiguous, and the 'Updated overnight' note adds a timing consideration.

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