Account overview

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuine context beyond that by disclosing that the call aggregates across several domains in a single request (balance, usage, credentials, ISP, invoices), but it says nothing about data freshness, aggregation window beyond 'this month', or response shape. Useful but modest added value on top of the annotations.

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?

Two sentences, front-loaded with 'One-call summary' and then the payload contents, followed by usage guidance. The enumeration is long but every item is informative rather than filler; a bulleted or grouped listing would read slightly cleaner but nothing is wasted.

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 input parameters and no output schema, the description carries the burden of telling the agent what comes back, and it does so by naming each data category included in the summary. Combined with the read-only annotation and the 'use first' routing hint, an agent has everything needed to decide to call it and to interpret the result.

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 and the schema is empty, so there is nothing for the description to disambiguate. Baseline for a no-parameter tool applies; no parameter-related gaps exist.

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 gives a specific verb and resource ('One-call summary of the DoubleData account') and then enumerates exactly what the summary covers: wallet balance, monthly bandwidth/requests/spend, top credentials, credential count, ISP subscriptions, open invoices. This lets an agent distinguish it from single-domain siblings like get_balance, get_usage, or isp_subscriptions without opening any schema.

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 explicitly states when to reach for this tool ('Use first when the user asks what they have, how much they used, or how much is left'), which effectively routes the agent ahead of the narrower per-domain siblings. It stops short of naming those alternatives or stating when not to use it, so it is strong but not fully exhaustive.

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