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

Annotations already declare the read-only, non-destructive safety profile and openWorldHint. The description goes further by disclosing the per-input-type return content and, importantly, the degradation behavior ('Returns available: false with a note when no estimate exists'), which the agent could not infer from 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?

Front-loaded with purpose, then usage trigger, then a compact breakdown of outputs per input type, ending with the failure case. Dense but every clause carries information; the per-type enumeration is slightly list-heavy but justified by the absence of an output schema.

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 return burden and does so by enumerating what each resource type yields plus the 'available: false' fallback. The remaining gap is that the required 'code' parameter's format and its role in selecting the resource type are left unexplained.

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 coverage is 100%, so baseline is 3. The single 'code' parameter is described only as 'Short code' in the schema, and the description implies the code selects among three resource types (prompt/context, dataset, model) but never explains the code format or how type is determined. It adds marginal value, not compensating detail.

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 a specific verb (estimate), resource (ContexteTech resource running cost), unit (euros), and data source (the week's list prices). This clearly distinguishes it from siblings like fetch, search, and load_resource, which have no cost dimension.

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 says when to use it: 'when the user asks about cost, budget or the cheapest model.' Clear trigger context, though no exclusions or alternative routing are named (no sibling covers cost, so that omission is minor).

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