search_instruments

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

Discloses contains/prefix matching, immutability of instrument IDs, and rate limit sharing beyond readOnlyHint annotation. Comprehensive behavioral context.

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?

Well-structured: purpose first, then matching behavior, return format, and rate limit. Every sentence adds value, no fluff.

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?

Covers purpose, parameter behavior, return format, rate limits, and caching guidance. Output schema is described explicitly. Complete for a search tool.

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 covers parameters (100% coverage), but description adds crucial detail on how query matching works, adding value beyond schema.

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?

Description clearly states searches instruments by ticker symbol and returns candidate matches. Specifies matching behavior (contains/prefix) which distinguishes from exact lookup tools like get_instrument_details.

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?

Provides explicit guidance to verify internalSymbolFull before using instrumentId. Does not explicitly contrast with siblings but gives clear context for correct use.

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