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

With no annotations, the description carries the full burden. It discloses that results are capped at 20 rows server-side and returned as a markdown table, which is helpful. However, it does not mention authentication requirements (e.g., OAuth) or side effects. This is a minor gap given the tool is read-only.

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 wasted words: first sentence states purpose and supported indices, second gives output format and cap. Highly concise and 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 is fairly complete for a read tool: purpose, supported inputs, output format, and limitation (cap). It lacks explicit mention of auth prerequisites, but output schema covers return structure. Minor gap, but sufficient overall.

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 description coverage is 80%, so the schema already explains most parameters. The description adds context about the output limit (20 rows, server-side cap) but does not elaborate on parameter meanings beyond the schema. Baseline 3 is appropriate.

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 'Get top movers for a market index' with a specific verb and resource, and adds 'Schwab's curated mover screener' for context. It also mentions the output format and row limit, distinguishing it from sibling tools like get_stock_quote or get_price_history.

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 lists supported indices ($SPX, $DJI, $COMPX) and explicitly states unsupported ones ($VIX, $NDX, etc.), but does not provide when-to-use guidance versus other market tools like schwab_get_stock_quote or schwab_get_price_history. No explicit alternatives or exclusions are given.

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