latest_trading_day

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

No annotations are provided, so the description carries the full burden. It discloses the portal lag and that 'today' is often empty, which explains the tool's behavior. However, it doesn't explicitly state side effects or error conditions, and doesn't confirm read-only status beyond inference.

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 three short, purposeful sentences plus an Args line. It's front-loaded with the main purpose, and every sentence adds value.

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 one-parameter utility, the description is sufficiently complete: it explains what, why, and when to call it, plus the parameter. The output schema can handle return value documentation. It could briefly mention edge cases like no valid date found, but it's not a significant gap.

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?

The schema provides only a type and default for on_or_before, with no description, so coverage is 0%. The description compensates by specifying the format (YYYYMMDD) and the meaning ('search back from'), plus the default behavior. This fully explains the parameter.

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 uses a specific verb 'Resolve' and clearly identifies the resource: the most recent date with ETF data. This distinguishes it from sibling tools that operate on ETFs, quotes, history, etc., making it clear this is a date-resolution utility.

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 explicitly instructs to 'Call this before assuming any date is usable,' providing clear timing guidance. It explains the portal lag context, which tells the agent when to use this tool, though it doesn't name alternative tools or state when not to use it.

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