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

Annotations already declare readOnly/openWorld/destructive flags, yet the description still adds real behavior: city/zip/asn targeting doubles traffic consumption, and specific cities or providers may be unavailable. It does not say whether generating lines reserves anything against the plan or how quickly newly requested geos become available.

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?

Front-loaded with the core action, then session modes, then optional geo targeting and cost caveat — a logical order with no filler. A few clauses pack multiple facts (ports plus duration plus cost) tightly enough to require a second read.

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?

For a 10-parameter tool with no output schema, the return shape is only partially covered: it says rotating yields 'one line' and sticky 'one IP per port', but never ties the count parameter (default 5, max 100) to how many lines come back, leaving the response cardinality ambiguous.

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?

With schema coverage at 50%, the description compensates for the weak spots: it explains session semantics, that country accepts ISO codes and comma-separated lists, and that state/city/zip/asn are precise-geo options. It says nothing about count, format, or protocol, though those three are enum/default-documented in the schema itself.

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?

"Generate ready-to-use proxy strings for a plan" names a specific verb and resource, and no sibling tool (get_account, get_plan, get_prices, list_plans) produces proxy strings, so the boundary is obvious without opening the 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 gives concrete decision criteria for the main branch point: 'rotating' for an IP that changes per request versus 'sticky' for a held IP per port lasting 1-120 minutes. It stops short of explicit when-not-to-use guidance or stating prerequisites such as the plan needing active proxy entitlement.

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