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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered by structured data. The description adds nothing about response shape, aggregation window, units of cost, or scope of the returned data, so it cannot compensate.

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?

Short, but the text is wasteful: the same endpoint path appears twice plus an operation ID, with no front-loaded statement of purpose. Brevity here reflects under-specification rather than efficiency.

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 tool with an undocumented nested query parameter and no output schema, the description should explain what cost data is returned and how to filter it. None of that is present, so an agent cannot invoke it correctly without trial and error.

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 0%, and there are two parameters including a free-form 'query' object with additionalProperties: {}. The description gives no hint about date ranges, filters, grouping, or what keys 'query' accepts, leaving the caller to guess entirely.

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 merely repeats the endpoint path '/api/subscription/ai-token-cost' twice and never explains what the resource actually represents (e.g. cost breakdown of AI token consumption for the subscription). A nearby sibling, get_subscription_ai_usage, is not distinguished, so an agent cannot tell which to call.

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?

There is no statement of when to use this tool versus get_subscription_ai_usage or get_subscription_usage_summary. The only guidance-like text, 'describe_operation provides native request schemas,' is a schema-discovery pointer rather than a usage condition.

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