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

Annotations show readOnlyHint=false, implying a write operation, but the description adds key behavioral context: the instrument appears in GetMyPortfolio's 'Watching (not held)' section with no quantity/cost/value, option contracts are verified against live data before storage, and selling out later keeps the instrument on the list. This goes 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?

The description is organized into three concise paragraphs: core function/effect, option-specific parameter guidance, and an edge case. Each sentence adds necessary value with no redundancy, and the main purpose is front-loaded.

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 description fully covers selection and invocation criteria: exact parameters, behavior, and edge cases. Although there is no output schema, the description adequately conveys what the agent needs to know to use the tool correctly, including the absence of position-related fields in the display.

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?

While the schema covers all parameters with descriptions, the description adds important semantic constraints: for options, both ticker and optionContract are required, and ticker means the underlying ticker. The reference to AddPortfolioLot's format and the verification step provide meaning not present in the schema.

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 the tool's function: adding a stock or option contract to a portfolio watchlist without recording a position. It distinguishes from AddPortfolioLot by emphasizing 'without recording any position' and from UnwatchInstrument implicitly, making the purpose unambiguous.

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 explicit when-to-use guidance: choose this when you do not want to record a position. It also gives precise instructions for options (both underlying ticker and OCC symbol, exactly as AddPortfolioLot takes them) and clarifies the edge case of watching an already-held instrument.

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