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

With no annotations, the description carries the full burden, and it does add some behavioral context: 'PRO' signals subscriber-tier access and 'max 30' bounds the lookback window. However, it does not explicitly confirm read-only behavior, mention rate limits, or describe return units, leaving meaningful 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 a single tightly packed sentence, front-loads the core resource and aggregation, and includes only the useful 'PRO' marker and max-days constraint. There is no wasted text.

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 simple no-output-schema tool, the description explains the returned aggregates but not the exact return shape, price units, time zone, or behavior when the optional days parameter is omitted. These are modest but real completeness gaps.

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 67%: postcode and access_token are already documented in the schema, while the description adds crucial meaning for the undocumented days parameter via 'last N days (max 30)'. That extra constraint meaningfully improves 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 names a specific resource (Agile import price) and aggregation (daily average/min/max) over a defined range (last N days), which is clearly distinct from slot-level or window-finding siblings. Sibling differentiation is implicit rather than explicit, so it falls short of a 5.

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 provides a use context ('for budgeting and tariff comparison') but does not state when to choose this tool over all_slots, cheapest_slots, best_window, or export_rates. The usage guidance is therefore implied rather than explicit.

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