Cross-Index GEX

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

Annotations already declare readOnlyHint=true, so the safe read nature is known. The description adds some behavioral context by explaining the tool's purpose ('to understand market-wide positioning') and the default ticker behavior, but does not disclose additional traits such as data freshness, rate limits, or output format specifics. This is acceptable given the read-only 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?

The description is well-structured with an introductory sentence, a usage bullet list, and separate Args/Returns sections. It is concise and informative. Minor redundancy exists between the first two sentences ('Compare GEX across major indices' and 'Shows gamma exposure comparison...'), but overall every section earns its place.

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 1-parameter read-only tool, the description covers the essential aspects: what the tool does, when to use it, what arguments it takes, and what it returns. The return description ('GEX comparison across indices') is somewhat generic, but given the tool's simplicity and the readOnlyHint annotation, the information is sufficient for correct invocation.

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 coverage is 0% (the schema property has no description), so the description must compensate. It does so effectively with an Args section that explains the tickers parameter: 'Comma-separated tickers or None for defaults (SPY,QQQ,IWM,DIA)'. This provides format, default behavior, and concrete example tickers, far exceeding the schema's bare type definition.

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's function with a specific verb and resource: 'Compare GEX across major indices' and 'Shows gamma exposure comparison between SPY, QQQ, IWM, and other major indices'. It distinguishes itself from sibling tools like get_gex (which likely handles a single index) by explicitly focusing on cross-index comparison.

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 explicit usage guidance with a 'Use this tool when the user asks about' list covering three specific scenarios. This gives clear context for when to use the tool, though it does not explicitly state when not to use it or mention alternatives like get_gex for single-index GEX analysis.

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