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

Annotations already declare the tool as read-only, idempotent, and non-destructive. The description adds substantial behavioral context: it explains the three 'kind' endpoints, the distinction between them, and what each returns (e.g., 'endpoint_weights map' for usage). No contradictions 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 well-structured and concise. It front-loads the core purpose ('Your mf_ key's account view'), then uses bullet-like clarity to list the three kinds. Every sentence adds value—no fluff or repetition. Despite moderate length, it is efficient.

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 presence of an output schema (not shown but noted), the description covers all necessary context: what the tool does, the three possible views, their API endpoints, and the purpose of self-throttling. It is complete for a read-only informational tool.

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 only parameter 'kind' is fully documented in both the schema and description. The description goes beyond the schema by explaining each enum value's meaning, the default behavior ('account' if empty/unknown leads to a menu), and mentions specific endpoints, which provides rich semantic value.

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 it provides the account view for the mf_ key, grouped by 'kind', and lists the three specific sub-views (account, usage, tiers) with their corresponding API endpoints and a brief summary of what each returns. It uses a specific verb ('read') and identifies the resource ('account / usage / tiers'), making the tool's purpose unambiguous.

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 explicitly advises using the tool to 'self-throttle by your remaining quota', which is a clear use case. It also explains the behavior for empty/unknown kind. However, it does not explicitly exclude alternative tools or describe when not to use it, but the context signals and sibling list (e.g., 'analyze', 'backtest') imply this is the only tool for account/usage/tier information.

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