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

readOnlyHint=true already tells the agent this is a safe read, so the description's added value is content disclosure — it states the balance combines allowance and purchased minutes and that reset timing is included. It still doesn't say what happens at zero balance or in which timezone the month resets, but for a quota readout this is solid extra context.

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 sentence with the resource, the composition of the balance, and the reset timing, all front-loaded. Nothing is padded or redundant.

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, the description must convey the return content, and it does — remaining minutes plus reset date. Minor gaps remain (units, behavior when exhausted, how this differs from get_video_call_access), but nothing blocks a correct call.

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 no parameters, so there is nothing to disambiguate and the baseline 4 applies. The description adds no argument syntax because none exists, which is correct.

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 resource and scope: video-call minutes remaining this month, explicitly defined as allowance plus purchased, along with the reset timing. That is far more precise than a restated name. It does not, however, distinguish itself from related siblings such as get_video_call_access or get_client_session_usage, leaving the agent to infer the boundary.

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?

Usage is only implied: an agent would reasonably call this before start_instant_video_call or join_session_video_call to confirm quota. There is no explicit when-to-use statement, no exclusion, and no pointer to the sibling that covers access entitlements.

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