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

Annotations only cover read-only/idempotent/non-destructive, and the description adds real behavioral context the annotations cannot: the call invokes a model that is billed to the caller's provider key (or the platform's), plus an explicit failure mode (sandbox self-registered keys get 403 until a person claims the workspace). It stops short of describing cost magnitude, latency, or return shape.

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, front-loaded with the purpose, then inputs, then billing/auth constraints; there is no filler. The input enumeration sentence is slightly list-like and duplicates schema detail, keeping it from a 5.

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 tool with no output schema, the description never indicates what an estimate looks like (per-country amounts in the requested currency, one entry per country, etc.). Auth, billing, and parameter behavior are well covered, but the return-value gap is a real omission for a billed model call.

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 schema already documents all five parameters, including the EUR default and the low/medium/high enum. The description restates the same facts (countries as names or ISO codes, currency default) without adding syntax, formatting, or constraint guidance beyond the schema.

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+resource ('estimate what a task would cost to do by people across countries'), which is clearly distinct from price-computation siblings like compute_price or ask_pricing_analyst. It does not explicitly name or contrast an alternative tool, so it falls short of a 5.

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 tells the agent which inputs to pass and states prerequisites (claimed Last Price credential, claimed workspace), which implies when the tool is callable. However, it never contrasts this with adjacent tools such as compute_price, get_cost_analytics, or list_costs, so selection guidance is left to inference.

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