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

With no annotations, the description does real work: it discloses that the comparison is metadata-only and needs no image fetch, that it defaults to the two newest renders, and that `unstable` is reported for nondeterministic previews. It omits auth/permission implications and any pagination or identifier-resolution behavior.

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?

Front-loads the core action in the first sentence and packs defaults, mechanism, and the `unstable` caveat into three tight sentences. The embedded aside about timelines being collapsed distinct renders is slightly elliptical but still earns its place.

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?

An output schema exists so return values need not be explained, and the description covers the comparison mechanics and the `unstable` signal. However, with zero annotations and a non-obvious anyOf parameter identity scheme, the definition leaves an agent without guidance on which identity form to supply or what access it needs.

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 only 17% and five of six parameters are undocumented there. The description only implicitly explains `from`/`to` via the default-to-newest behavior; the dual identity options (uri vs catalog+previewId) and the anyOf requirement are not addressed at all.

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?

States a specific verb and resource: comparing two recorded renders of a preview, and clarifies it is a metadata comparison rather than an image fetch. This distinguishes it in spirit from catalog_diff_semantics and catalog_history_read, though it never names those siblings 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?

Gives a concrete motivating scenario ("did the last publish move this preview?") and states the default behavior of comparing the two newest renders. It lacks explicit when-not-to-use guidance or a named alternative such as catalog_diff_semantics for semantic comparison.

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