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

With no annotations present, the description carries the full burden of behavioral disclosure. It only states that the tool 'gets' data and vaguely mentions average changes, but does not disclose return format, filtering behavior, or any limitations. This is minimal disclosure for a tool that may produce varying results based on optional parameters.

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 concise at two sentences, but includes the redundant phrase 'using the Market Sector Performance Snapshot API' which repeats the tool's name. Overall, it communicates the core purpose without excessive verbosity, though the second sentence adds limited new information.

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 relatively simple snapshot tool, the description provides enough to understand the general purpose, but it lacks any detail about the response contents or structure, especially since there is no output schema. It also does not clarify how it differs from closely related sibling tools, leaving some contextual gaps.

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 input schema provides full descriptions for all three parameters (date, sector, exchange) with format examples, achieving 100% coverage. The description adds no additional semantic meaning, such as whether sector and exchange are optional filters or how they interact, so the baseline of 3 applies.

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 that the tool retrieves a sector performance snapshot via the Market Sector Performance Snapshot API, with a focus on analyzing industry performance based on average sector changes. However, it does not explicitly distinguish between sectors and industries, which could cause confusion with the similarly named sibling tool getIndustryPerformanceSnapshot.

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 no guidance on when to use this tool versus alternatives such as getHistoricalSectorPerformance or getIndustryPerformanceSnapshot. It lacks any conditions, prerequisites, or exclusions, leaving the agent without direction for tool selection in a crowded market-data landscape.

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