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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description still adds real value by listing the response composition an agent needs for diagnosis and by closing off the mutation path ('changing tariff and payment are not via the assistant'), preventing a futile search for a write sibling.

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?

Three sentences with the purpose front-loaded, then the diagnostic use case, then the read-only boundary. The middle enumeration of limits and features is long but each item is load-bearing because there is no output schema. Minor density cost, no wasted sentences.

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 carries the full burden of describing the return value and does so thoroughly — limits with remainders, payment status, remaining days, and capability list. For a one-parameter, annotation-covered read tool, nothing an agent needs 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?

There is a single parameter and the schema documents it at 100% coverage (workspace_id sourced from workspace://list). The description adds no syntax, format, or default detail beyond that, 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?

The description names a specific verb+resource (returns the account tariff in full) and enumerates exactly what comes back: tariff code, payment status, days remaining, per-resource limits, and capability flags. It is unmistakably a workspace-tariff read, not a catalogue lookup, although it never names sibling get_tariff_list explicitly to draw the contrast.

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 gives an explicit triggering context — 'look here when an action was rejected because of the tariff' — and explains what to look for (limit exhausted, term expired, capability absent). It also states the counterpart case (changing/paying for a tariff is not done through the assistant), which implicitly bounds usage, though no sibling alternative is named.

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