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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile needs no restating. The description does add something the annotations lack: a per-call quota ('cost: 1 credit') and the exact deterministic formula. It says nothing about return type or behavior when inputs are non-numeric or the wrong length, which is the main remaining gap.

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?

A single front-loaded sentence gives the operation, the domain constraint, and the formula, with the cost note appended compactly. The formula is arguably redundant for an agent but is short and reinforces determinism, so nothing meaningfully wasteful remains.

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 two-parameter pure-computation tool with full schema coverage and complete safety annotations, the description supplies everything needed to call it; the formula implies a numeric scalar result. Minor omissions are the lack of sibling differentiation and of input-error behavior.

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 both parameters are already documented as '[x, y]' coordinate arrays. The description only restates 'two points in a 2D plane' and adds no format detail such as whether a CSV-style string is accepted or what happens on dimension mismatch, so it sits at the baseline.

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 states a specific verb and resource ('Computes the Euclidean distance between two points in a 2D plane') and even gives the exact formula, so the operation is unambiguous. It does not, however, distinguish itself from the sibling 'calculate_distance' or from 'cosine_similarity', leaving the agent to infer which distance tool to pick.

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?

There is no explicit when-to-use guidance and no named alternative. The only implicit scoping is 'in a 2D plane', which hints that 3D or higher-dimensional inputs are out of scope, but the agent must infer that and must guess how this differs from the sibling calculate_distance.

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