get_plan_performance

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

With no annotations, the description carries the full burden. It discloses the return format (JSON string) and the specific metric fields (subscribers, total revenue, avg revenue per merchant). However, it does not note that this is a read-only operation, potential data inference caveats, or any error/timezone behaviors. The 'inferred pricing tier' hint adds some transparency but is not elaborated.

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 well-structured docstring with Args and Returns sections, front-loading the main purpose. Every sentence is necessary, with no fluff or repetition.

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 with two optional parameters, and the description covers the parameters, accepted values, return format, and key metrics. It lacks context on when to use it or what 'inferred pricing tier' means, but the presence of an output schema (per signal) and the low complexity make this moderately complete.

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 0%, but the description fully explains both parameters: app_id is 'Filter by app (optional)' and period lists all accepted formats including '7d', '30d', '90d', '1y', and an explicit date range. This adds essential meaning beyond the bare 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 opens with a clear verb and resource: 'Get metrics per pricing plan tier.' This specifies exactly what the tool does and distinguishes it from sibling analytics tools by focusing on plan-tier-level metrics rather than overall revenue or churn.

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 implies usage through its purpose but does not explicitly state when to use this tool over alternatives like get_revenue_summary or get_mrr_movement. No exclusions or alternative references are provided, leaving the agent to infer applicability.

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