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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions what details are returned but does not state whether the tool is read-only, how it handles invalid or missing ISINs, or the response structure. This leaves significant gaps for an agent deciding whether invocation is safe and correct.

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 compact, consisting of two sentences, and front-loads the primary action. Minor fluff ('Easily', 'using the FMP ISIN API') could be trimmed, but overall it's efficient and readable.

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 one-parameter lookup with no output schema, the description is minimally adequate. It states the main purpose and some return fields, but omits details about error behavior, response format, and usage context relative to sibling tools, which would improve completeness.

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 100% – the only parameter 'isin' has a description. The tool description adds no extra semantic value about the parameter format, validation, or examples, so it meets the baseline but does not exceed it.

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 identifies the tool's function: searching and retrieving ISIN-related data. It names the resource (ISIN) and lists example output fields (company name, stock symbol, market cap), distinguishing it from sibling tools like searchCUSIP and searchCIK. However, the phrase 'retrieve the ISIN' is slightly misleading since the input is actually an ISIN, not the output.

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 no guidance on when to use this tool versus alternatives such as searchCUSIP, searchCIK, or searchSymbol. It does not mention any exclusions or specific use cases, leaving the agent to infer from the tool name alone.

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