get_mrr_movement

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

No annotations are provided, so the description carries the burden of disclosing behavior. It does mention the return format (JSON string) and that it compares current vs previous period, which is useful. However, it does not explicitly state that this is a read-only operation, nor does it disclose any edge cases or calculation caveats, leaving some gaps.

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 and well-structured: a one-line purpose, a short Args section, a clarifying sentence, and a Returns section. It is front-loaded with the core purpose, and every sentence contributes necessary information without redundancy.

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?

Given the tool's simplicity (2 optional parameters, no nested objects), the description is complete. It covers the purpose, parameter semantics, and return format, leaving the agent with enough information to invoke it correctly. The presence of an output schema is complemented by the description's explicit listing of return fields.

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 has 0% description coverage, but the description fully documents both parameters: app_id is described as an optional filter, and period has its allowed values ('7d', '30d', '90d', '1y', or a date range) explicitly listed. This adds significant meaning beyond the schema's plain type and default fields.

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 'Get MRR movement breakdown' and enumerates specific components (new, expansion, contraction, churn, reactivation), making the tool's purpose concrete and distinct from broader revenue metrics. It further clarifies scope by stating it shows how MRR changed between current and previous period, which distinguishes it from sibling tools that focus on summaries or churn only.

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 clearly implies when to use this tool (whenever an MRR movement breakdown is needed) and provides context for the period parameter with valid values. However, it does not explicitly mention alternatives or state when not to use this tool, so it falls short of full guidance.

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