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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety bar is low. The description still adds real context beyond them: an admin-scoped token is required, the scope is a fixed set of exactly three workspaces, and spend/call figures are bucketed to the UTC day. It does not say whether the numbers are cached or how fresh 'updatedAt' is, which is the only material gap.

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?

Front-loaded with the scope and the workspace names before the auth constraint and return shape, and the parenthetical field list is dense but readable. It is a single long compound sentence plus a return signature, so it is efficient though slightly overstuffed for such a simple list call.

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?

There is no output schema, and the description compensates by spelling out the exact return object shape including day, platformDailyCents, and per-workspace fields. Combined with the auth requirement and the fixed three-workspace scope, an agent has everything needed to call it and interpret the response.

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 tool takes zero parameters, which is the baseline-4 case. The description correctly avoids inventing parameter guidance and instead spends its words on scope and return shape.

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 the resource precisely ('the three provider workspaces every model call is billed to by its purpose') and enumerates the actual workspaces plus the fields returned, so an agent knows exactly what comes back. It also names the underlying endpoint. It does not differentiate itself from likely-adjacent siblings such as merjax_ai_cost_summary or merjax_set_ai_workspace_quota, so it stops 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 gives a hard prerequisite ('Site admins with an admin-scoped token only'), which is genuine when-to-use context. However, it never states when to prefer this over merjax_ai_cost_summary for spend questions, nor what to do if the caller is not an admin. Usage is implied rather than routed.

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