lookup_symbols

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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is established. The description adds valuable behavioral context by stating it 'Returns comprehensive data including ATH, 52-week highs/lows,' which is useful for output expectations. No contradictions with annotations.

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 sentences: first clearly states purpose, second provides usage guidance and return info. Front-loaded and concise, with zero redundant phrasing. Every sentence serves a distinct purpose.

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?

With only 2 parameters (fully described in schema), an output schema, and strong annotations, the description covers purpose, usage, and return data. It also addresses the indexing edge case, providing enough context for an agent to decide appropriately. Complete for its scope.

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 100%, with both parameters (symbols and columns) fully described in the schema via descriptions. The description itself adds no parameter-level detail. Baseline of 3 is appropriate since the schema carries the burden.

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 action ('Look up specific symbols by ticker') and the resource (stocks, indexes, ETFs). It explicitly distinguishes from screening tools by noting it handles indexes not found via screening, providing context on scope.

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?

Explicit guidance: 'Use this for direct symbol lookup including market indexes... that cannot be found via screening.' This gives specific when-to-use context and implicitly contrasts with screening tools. Alternative search_symbols is not mentioned, but the direct lookup focus is clear.

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