buy

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

Discloses behavioral traits: weighted-average cost, new position opening, ledger cash movement, and no real orders. Annotations (destructiveHint=true) are consistent and description adds richer 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?

Concise and well-structured: purpose first, then behavior, instructions, args, returns. Every sentence is informative and earns its place.

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 all necessary aspects: parameter descriptions, return values (updated position summary or error), and behavioral constraints. Adequate for a complex tool with 6 params and 3 required.

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%, baseline 3. Description adds value beyond schema with examples (e.g., yfinance ticker formats), default values, and parameter explanations (e.g., unit_label default '股').

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 it records a buy in the local ledger, adding to existing positions or opening new ones. The verb 'buy' is specific and distinguishes from sibling tools like 'sell'.

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?

Explicitly instructs to confirm symbol, units, and price with user before calling, and clarifies this is bookkeeping, not a real order. Lacks explicit when-not-to-use but is implied by context.

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