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

With no annotations, the description fully carries the behavioral burden and does so thoroughly. It discloses the return shape (verdict, plain-language problem, alternative interpretation), states that no coordinate transformation occurs, and guarantees local computation with no network call or quota. This gives an agent a complete picture of side effects and non-effects.

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?

Every sentence earns its place: purpose, failure modes, input prescription, output summary, and capability boundary. The description is dense but not bloated, and the most decision-relevant information is front-loaded.

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 2-parameter validation tool with a full output schema present, the description covers what matters: what the tool checks, why it exists, what inputs to provide, what outputs to expect, and what it will not do. An agent has everything needed to select and invoke it correctly without additional context.

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?

The schema already covers 100% of parameters, so the baseline is 3; the description adds real value beyond that by explaining why parameters are named x/y rather than lon/lat, giving concrete EPSG examples, and advising that 'a few dozen is plenty'. This helps the agent construct sensible inputs without restating schema content.

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 first sentence gives a precise verb-check, a specific resource (a dataset's declared CRS against its own coordinates), and a concrete use moment ('before you draw it on a map'). It also names example failure modes (swapped axes, degrees labelled as metres), making the tool's job unmistakable and distinct from the many geo sibling tools.

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?

The description clearly frames when to use it ('before you draw it on a map') and explicitly excludes a major misuse case ('a sanity check, not a reprojection: it never transforms coordinates'). It does not name an alternative tool for reprojection or other coordinate operations, so it stops just short of explicit alternative routing.

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