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

readOnlyHint already covers the safety profile, and the description adds genuinely useful context beyond it: the hitl_channels sub-object silently degrades without the hitl:read scope, and the tool will not unlock via start_login so the client must be authenticated through /mcp first. It does not mention payload size, rate limits, or freshness of the aggregates, which keeps it below 5.

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 first sentence front-loads the payload contents and the second anchors it to the dashboard; the access block is short and actionable. Minor slack: the authentication instruction is repeated in emphatic form ('then call this tool again' / 'start_login does NOT open this tool'), which costs a few words but does prevent a real failure mode.

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 an output schema present, the description only needs to explain scope, prerequisites and caveats, and it does: aggregate contents, per-sub-object scope requirement, account/auth prerequisite, and the account-wide quota exception. Complete enough to call correctly; only the absence of freshness/pagination expectations leaves a small gap.

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 description coverage is 100%, so both profile_id and environment (including the 'quota stays account-wide' caveat and the production default) are already fully documented in structured fields. The description adds no parameter-level meaning beyond the schema, so the baseline 3 applies.

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 and a clearly bounded resource ('one-call account snapshot') and then enumerates exactly what the snapshot contains: quota + projection, request health, channel completion rates, HITL counts, API key count. The enumeration itself distinguishes it from narrow siblings like get_usage, get_balance and get_api_key_usage, and the 'same data the dashboard home renders' anchor makes the aggregate scope unmistakable.

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?

With 'one-call snapshot' and the dashboard-home analogy, an agent can infer this is the preferred starting point over stitching together get_usage/get_balance/get_api_key_usage. The access paragraph gives concrete when-to-use conditions (must have a Proof account, must authenticate this client, call again afterwards). It still never explicitly names an alternative tool or when NOT to use it, so it stops short of 5.

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