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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false. The description adds a genuinely non-obvious behavioral trait the annotations do not cover: the call is free and consumes no lookup quota, which materially affects how aggressively an agent should call it.

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?

A single front-loaded sentence with no filler. Every clause carries information: what is returned, the time window, and the cost profile.

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?

With no output schema and no parameters, the description carries the burden of describing returns and does so by enumerating the exact fields (plan, used, remaining, monitor count, rate limit). Nothing an agent needs to call this correctly is missing.

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?

Zero parameters, so the baseline of 4 applies; the schema is an empty object with additionalProperties=false. The description correctly implies no arguments are needed and adds the meaningful scoping detail that the usage window is the current UTC month.

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?

Names a specific verb ('show') and enumerates exactly what is returned: plan, lookups used/remaining for the UTC month, monitor count and rate limit. An agent can immediately distinguish this self-introspection tool from the lookup/history/watchlist siblings.

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 clause 'Free; does not cost a lookup' gives a clear conditional cue — it is safe to call at any time, e.g. to check quota before batch_lookup. It stops short of naming an explicit alternative or a when-not-to-use condition, so it is strong context rather than full routing guidance.

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