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

Annotations already indicate read-only, idempotent, and non-destructive behavior, so the bar is lower. The description adds valuable context by stating it is 'Live', returns 'structured numbers', and is 'Keyless (Yahoo Finance)', which discloses the data source and auth requirement. It does not contradict 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 efficiently structured with a front-loaded summary, then defaults, usage, output type, and auth note. Every sentence adds value, and the dense but organized listing of asset classes avoids unnecessary words.

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?

Given the tool has only one optional parameter with full enum documentation, the description covers the critical context: what the tool returns, the default scope, how to narrow by region, the output format (structured numbers), and the fact that no key is required. No output schema exists, but the narrative description sufficiently explains the return value for an agent.

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% and the region parameter is fully described with an enum. The description goes beyond the schema by detailing the default headline composition (Asia + Europe + US futures + 10Y + DXY + oil + gold + BTC) and framing region as a way to 'drill into one group,' adding practical meaning to 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 clearly states the tool provides a live market snapshot for a recap, listing the exact asset classes covered (major indices, Treasury yields, FX, commodities, crypto) and how data is grouped by region. This distinguishes it from sibling tools like get_quotes or top_movers by focusing on a curated, group-level overview rather than individual quotes or movers.

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 gives clear context for when this tool is appropriate ('what happened in markets' recap), explains the default headline behavior, and instructs to 'Use region to drill into one group.' It does not explicitly mention when not to use it or suggest alternatives, but the default and region guidance provide solid usage direction.

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