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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable context beyond those: it says the tool 'fails closed' for unsupported versions and lists the comparison-safety fields `trend_suppressed` and `series_breaks`, which are useful behavioral details not present in 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?

The description is two sentences with front-loaded purpose, followed by key return fields, versioning constraint, and a sibling pointer. Every sentence earns its place; no redundancy or fluff.

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 read-only tool with rich annotations and fully documented parameters, the description covers the return fields (`latest value`, `canonical citation`, `trend_suppressed`, `series_breaks`), the versioning requirement, and the legacy alternative. No output schema exists, but the description provides enough detail about the response to be complete.

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%: both `slug` and `response_version` have clear descriptions in the schema. The description re-emphasizes that `response_version` must be 'v2' and that unsupported versions fail closed, but does not add new semantic meaning beyond what the schema already provides. Thus baseline 3 is appropriate.

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 opens with a specific verb+resource: 'Fetch an explicitly versioned compact indicator snapshot.' It clearly distinguishes this tool from the sibling `get_indicator` by noting the legacy tool remains pinned to its original v1 shape, so this is the v2 counterpart.

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 explicitly states the caller must pass `response_version='v2'` and that unsupported versions fail closed, giving a clear when-to-use constraint. It also names the alternative `get_indicator` for the original v1 shape, providing a direct sibling comparison.

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