get_performance

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

Annotations already establish that the operation is read-only and non-destructive. The description adds only a vague behavioral point—that results are price changes over 'usual reference periods'—without defining those periods or the response format. This is acceptable but not rich extra 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?

The description is a single compact sentence with no filler or repetition. The phrase 'usual reference periods' is vague, but that is more a precision issue than a conciseness issue.

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 no output schema and no parameter details, the description should clarify what the reference periods are, how exchange affects results, and what the return value looks like. It does none of these, so the agent must already know the domain-specific conventions.

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 0%, so the tool description carries the full burden of explaining parameters, but it never explains isin or exchange. 'Instrument' only loosely maps to isin, and the optional exchange parameter is not addressed at all.

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 states that the tool returns price changes for an instrument over reference periods, which gives a clear sense of the resource and outcome. However, it is a noun phrase rather than an explicit verb+resource statement, and it does not distinguish itself from siblings like get_price_history or get_quote.

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?

No guidance is given about when to use this tool instead of alternatives. There is no mention of get_price_history, get_quote, or get_stock_details, so the agent must infer the appropriate context solely from the tool name.

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