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

Annotations only say it is non-read-only, non-destructive and closed-world; the description adds material context the annotations do not: owner/sign-in authorization, the floor of already-committed charges, and the operational effect that both at_limit values stop paid usage while 'ask' leaves a note. These are real consequences of invoking the tool, not restatements.

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?

Dense and front-loaded with the authorization gate, and every sentence carries operational content. It is slightly telegraphic ('Both actions stop paid usage' only parses after the reader has seen the enum), but there is no filler.

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 two-parameter mutation with no output schema and no annotation detail, the description covers who may call it, the value constraint, the meaning of both enum choices, and the downstream effect. It does not state what a successful call returns or how usage/pricing is presented, which would complete the picture.

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 coverage is 0%, so the description must carry the param meaning and largely does: monthly_dollars is defined as an enforced limit covering base plan plus overages with a floor at committed charges, and the two at_limit enum values are behaviorally distinguished. The 0–10000 bound in the schema is not mentioned in prose, a minor residual gap.

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 and resource ('Change the enforced monthly limit') and scopes it ('the base plan and usage overages'), which is enough to separate it from top-up/checkout siblings. It stops short of naming an alternative tool by name, so differentiation relies on inference from the constraint language.

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?

Strong preconditions are stated: 'Owners only (needs sign-in)' and 'only to the amount the owner explicitly requested', plus a workflow step ('Show current usage and prices first') and an explicit prohibition ('Never raise a limit to bypass a paused call on your own'). No sibling tool is named as an alternative, which is the only gap.

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