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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds useful context by stating the diff runs only against locally cached, integrity-verified catalogs and that data 'comes back as it is.' The 'read-shaped tools only' line mostly duplicates the annotation, so incremental transparency is moderate.

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 first sentence is useful and front-loaded, but the rest contains boilerplate about the MCP server, sandbox, and a registry listing URL. This unrelated context adds length without helping an agent invoke the tool correctly.

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 tool with two required parameters, one deeply nested, and no output schema, the description is incomplete. It does not describe expected return values, how to construct the stack object, what toCatalogDigest refers to, or what 'diff' outcome looks like.

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 0%, and the description does not explain the meaning of 'stack' or 'toCatalogDigest' beyond the schema property names. The tool must compensate when schema coverage is low, but it does not, leaving an agent to infer parameter semantics from names alone.

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 uses a specific verb and resource: 'Diff a stack only against locally cached, integrity-verified catalogs.' It conveys the core action and its constrained scope. However, it does not explicitly differentiate among sibling stack tools like compose_stack or inspect_stack.

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?

No guidance is given for when to use this tool versus siblings or alternatives. The read-only and local-cache constraints are mentioned, but there is no explicit context for when an agent should prefer this tool, nor are alternatives named.

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