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

Annotations already establish readOnly/idempotent/non-destructive behavior, so the description's additional disclosure of return contents ('Returns elevation_m plus dataset resolution info') and operational constraints ('free registration (5K req/day)') provides useful context beyond structured data. The source/licensing note also helps set expectations, though API key requirements are only hinted at.

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 core function, followed by dataset options, return value, and source/licensing. Every sentence earns its place with no filler or repetition of schema details.

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 simple 3-parameter tool with an output schema, the description covers the key points: units, coordinate scope, dataset choices, return value hint, rate limit, and source. The only notable gap is the ambiguous 'free registration' — it doesn't explicitly say whether an API key is required — but this is minor given the tool's simplicity.

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%, and the description adds a small amount of extra meaning by noting SRTMGL1 is the default and clarifying dataset resolutions (e.g., 'COP30 (Copernicus 30m)'). This is helpful but largely redundant with the enum descriptions already present in the schema, so it stays 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 clearly states the tool queries terrain elevation at a specific latitude/longitude coordinate using global DEM datasets, with the verb 'Query' and the resource 'terrain elevation' clearly identified. The scope ('specific coordinate') distinguishes it from area/batch tools, though it doesn't name sibling tools explicitly.

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 phrase 'at a specific latitude/longitude coordinate' implies this tool is for single-point queries, suggesting it should not be used for areas or batches. However, it does not name alternatives such as opentopo.elevation.area or opentopodata.elevation.batch, nor state when those would be preferred, so guidance remains implicit rather than explicit.

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