Buy Proxy GB

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

Annotations declare a non-read, non-idempotent, non-destructive mutation, and the description adds material context beyond them: it discloses the return value ('proxy credentials and remaining balance') and the non-obvious trait that country_code is 'only a soft preference for provisioning,' which prevents agents from assuming geo-guaranteed allocation. It does not contradict annotations, though it stops short of describing billing/failure edge cases for a purchase action.

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?

Four tight sentences with zero filler: the core action and return value lead, followed by two routing sentences that each name a specific sibling tool. Every sentence earns its place, and it stays compact despite the API having 40 siblings.

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 wisely states what the call returns (proxy credentials and remaining balance), and it resolves sibling ambiguity by naming the two related tools and the sequencing between them. It could additionally flag explicit billing/payment side effects or failure behavior, but the mutating nature of a purchase is already visible via annotations and the title.

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 the baseline is 3 and the schema already documents all four parameters. The description earns a 4 by adding the crucial semantic nuance that country_code is a soft preference only, which materially changes how an agent treats that parameter, and by framing gb as the traffic volume being added within the purchase.

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?

States the action precisely — 'Purchase proxy traffic (GB) for a selected pool type' — with a clear resource (GB in a pool) and a specific verb. It differentiates itself from closely related siblings by pointing to virtualsms_generate_proxy_endpoint and virtualsms_set_proxy_targeting for related-but-different actions, so an agent can tell them apart without inspecting schemas.

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?

Explicitly names alternatives and the conditions that select them: use virtualsms_generate_proxy_endpoint for per-connection targeting (country/state/city/zip/asn) or a ready-to-use connection string, and virtualsms_set_proxy_targeting to persist a default targeting. The phrase 'after buying' also establishes the correct call ordering. This is the strongest possible routing guidance.

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