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

Annotations already declare readOnlyHint=true and idempotentHint=true. The description goes further by explicitly stating it 'cannot charge, refund, retry, settle, transfer, or move funds' and lists what data it excludes. This adds meaningful behavioral context beyond the annotations, covering non-mutating constraints and scope boundaries. It does not mention rate limits or auth, but those are not critical for this type of tool. The description adds value without contradicting 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?

Two sentences with zero waste. The first sentence states the primary purpose and the range limit; the second lists exclusions and non-capabilities. Information is front-loaded and every word earns its place. The structure is optimal for an agent to quickly grasp scope.

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 has an output schema, so return format is covered elsewhere. The description covers purpose, constraints, exclusions, and non-capabilities. It does not explicitly mention error handling or auth requirements, but for a read-only summary tool with strong annotations and output schema, this is adequate. A 4 reflects that it's thorough but could include explicit 'use when...' guidance to tie into usage guidelines.

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%, so the schema already documents gymId, endTime, and startTime with clear descriptions. The description adds the 'at most 31 days' range constraint, which is not in the schema and directly affects parameter usage. It also reinforces that the gym must be owned by the tenant. These additions give the agent useful context beyond the schema, so a 4 is appropriate.

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 verb ('Summarize') and resource ('recorded payment counts, status counts, and amount totals by currency') for one tenant-owned GymFlexa gym. It clearly distinguishes itself from sibling tools like get_gym_schedule_summary and show_gym_overview by explicitly listing exclusions (payment ids, processor data, etc.). The purpose is unambiguous and specific.

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 provides clear context on what the tool does and its constraints (read-only, at most 31 days, excludes sensitive data). It implicitly tells when to use it (when a payment summary is needed) but does not explicitly name alternatives or state 'use X instead of Y'. The exclusions hint at boundaries, but there's no direct guidance on choosing between this and get_gym_schedule_summary or show_gym_overview. This is a minor gap, so a 4 is warranted.

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