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

The description reveals a meaningful behavioral trait: 'Updates shares and average cost' – this goes beyond the annotations (which only say readOnlyHint=false). It doesn't disclose potential failure modes, exchange requirements, or reversibility, and with no supporting annotation detail, the description could carry more behavioral load.

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?

Two sentences with no filler. The core purpose is front-loaded and the side-effect is stated immediately, making it efficient and easy to parse.

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 6-parameter tool with no output schema and no meaningful annotations, the description provides essential info but omits important operational details: reliance on holding_id, behavior on sell that exceeds shares, trade date defaults, and what is returned after success. It is adequate but not complete enough to fully guide an agent without further schema inspection.

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%, so the baseline is 3. The description adds semantic linkage by tying 'buy or sell' to the type enum and explaining that shares and price_per_share affect average cost. This clarifies the meaning of parameters beyond their schema descriptions, so a 4 is warranted.

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 states a specific verb ('Record') and resource ('buy or sell trade for a portfolio holding'), and explains the side effect ('Updates shares and average cost'). This distinguishes it from sibling add_* tools like add_transaction or add_bookmark without needing to inspect the schema.

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 phrase 'for a portfolio holding' provides clear context for when to use the tool, and the buy/sell distinction frames the trade types. However, it does not mention alternatives or explicitly state when not to use it (e.g., if holding_id is invalid), so it falls just short of a 5.

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