compare_periods

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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds useful behavioral details: returns totals for both windows plus absolute/percent change, money in USD, and only two totals per metric. This goes beyond the annotations without contradicting them.

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 sentences, each dense with information. First sentence states purpose and window logic, second states returns, third gives usage guidance. No unnecessary words, well 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?

For a read-only tool with 3 optional parameters and no output schema, the description adequately explains the return structure (totals, change, USD) and limitations (no day-level breakdown). It provides sufficient context for an agent to use the tool correctly.

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%; each parameter has a description. The description adds minimal extra meaning—e.g., that 'days' defaults to 7 and 'metrics' defaults to a useful set. Baseline is 3, and the description does not significantly enhance parameter understanding beyond the schema.

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 compares account performance over back-to-back trailing periods. It specifies the verb 'compare', the resource 'account performance', and the exact window logic. It distinguishes from sibling 'get_daily_performance' by noting that this tool returns only two totals per metric.

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 states when to use the tool (comparing back-to-back windows) and when not to: if day-level shape is needed, use 'get_daily_performance'. This provides clear guidance on alternative tools.

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