get_indices

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

readOnlyHint=true already declares the read-only safety profile. The description adds meaningful behavioral context with 'sourced from ETF proxies', revealing data provenance and potential tracking differences from actual index levels. It also lists the exact return fields (symbol, name, price, change, change_pct), enhancing transparency beyond the annotation.

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?

Two concise sentences that are front-loaded with the resource name, list the return fields, and include the data-source caveat. Every word earns its place without 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?

Given a simple tool with no parameters, a readOnlyHint annotation, and a full output schema, the description fully covers what the tool does, which indices it covers, how data is sourced, and when to use it. No meaningful gaps remain.

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, so the baseline is 4 per the rubric. No parameter documentation is needed; the description focuses on output and use case.

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?

Clear specific verb 'snapshot' with explicit resources (S&P 500, Nasdaq 100, Dow, Russell 2000). The description inherently differentiates from sibling tools like get_quotes by scoping to a fixed set of major indices, making its purpose unmistakable.

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 phrase 'Quick orient before deeper analysis' explicitly communicates the intended use case: a fast overview before diving into more detailed tools. It does not name alternative tools or exclusions, but the context is clear.

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