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

Annotations already declare readOnlyHint=true and destructiveHint=false, indicating a safe read operation. The description adds that it provides aggregate statistics over a period, which is useful but doesn't go beyond the annotation's safety profile. There's no contradiction, but the description doesn't add significant behavioral context beyond what annotations already imply, such as whether results are cached or computation occurs.

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 a single, short sentence that is front-loaded with the key purpose. It's concise and contains no waste, though it could have included a bit more specificity about what 'aggregate statistics' includes.

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 tool is simple (one parameter, no required fields, output schema exists), and the description adequately covers the purpose. With rich annotations and an output schema, the description doesn't need to explain return values or structures. It's mostly complete, though a bit more detail on what metrics are included could help.

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 100% for the single 'period' parameter, with a clear description and enum values. The description itself doesn't add parameter-level details, but the schema fully covers it. Baseline 3 is appropriate since the schema handles the parameter semantics.

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 it provides aggregate AI signal performance statistics over a specific period, using specific verb (get) and resource (signal performance statistics). It's distinguishable from siblings like get_signal_details (which likely returns individual signal details) and get_market_stats (market-wide stats), though it doesn't explicitly differentiate.

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 a clear when-to-use context ('when the user asks for aggregate AI signal performance statistics over a specific period'). However, it doesn't explicitly mention alternatives or when not to use this tool, so it lacks exclusionary guidance that would help differentiate from other statistics tools.

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