search_instruments

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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is fully covered by structured data. The description adds a modest behavioral nuance: the fundamental mode returns a different shape of data than a plain lookup, which is a mode-dependent return trait rather than mere repetition. It says nothing about result limits, pagination, or whether the search is exact-match, so it does not go far beyond the 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?

A single front-loaded sentence with no filler; the primary capability comes first and the secondary fundamental mode follows. Slightly muddy because it compresses three distinct behaviors into one compound sentence that reads as one capability.

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?

The output schema exists, so return values need not be explained, and annotations cover safety. But the tool exposes five search types and the description addresses only three, leaving symbol_regex and description_regex behavior entirely to the schema, and one required plus one optional parameter with a default is thin coverage for a multi-mode 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 description coverage is 100%, so both parameters are already documented in the schema, including the enum values and the example query. The description restates symbol/company-name/fundamentals use but adds no syntax, matching behavior, or regex-mode detail beyond what the schema provides. Baseline 3 applies when the schema does the heavy lifting.

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?

States a concrete verb ('look up') plus the resource ('instruments') and enumerates the lookup modes: by symbol, by company name, or fundamentals for a symbol. It is distinguishable from siblings like get_quotes or get_price_history, which retrieve data rather than resolve identifiers. It stops short of naming a sibling, so it is clear but not maximally differentiated.

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 three clauses imply when each mode applies (symbol lookup, name lookup, fundamentals), which is useful implied guidance. However, there is no explicit when-to-use/when-not framing, no guidance on choosing among the five enum values, and no routing to alternatives such as get_quotes once a symbol is resolved.

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