pct_change

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

Annotations already declare readOnlyHint, destructiveHint, and idempotentHint, so the description's behavioral disclosure is minimal. It adds that the output is a percentage change, but doesn't elaborate on calculation details or edge cases. No contradiction with annotations.

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 extremely concise—two short sentences—with no redundant information. It front-loads the core purpose and immediately gives usage examples.

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 simple nature of a percentage change tool and the presence of safety annotations, the description covers the basics. However, it lacks details on return values, edge cases, or parameter formats, which could be problematic for agents unfamiliar with the domain.

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 only 25% (only 'period' has a description). The description mentions 'YoY, QoQ, MoM' which helps with the 'period' parameter, but does not explain 'entity', 'indicator', or 'time'. With low schema coverage, the description should compensate but fails to do so.

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 'Period-over-period percentage change for an indicator' with specific examples like YoY, QoQ, MoM. It distinguishes itself from sibling tools like 'calculate', 'lag_analysis', and 'compare_entities' by focusing on growth rates.

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?

It explicitly says 'Use for growth rates (YoY, QoQ, MoM)', providing clear context for when to use this tool. However, it does not specify when not to use or mention alternatives, which would make it a 5.

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