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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and openWorld, so safety is covered. The description adds genuine context: what the README conceptually is (the Markdown document on the variant page in GraphOS Studio) and that the response includes last-updated metadata, which annotations do not convey.

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 purpose and return shape are front-loaded in the first sentence, and the remaining sentences are short utility lines. The GraphOS Studio sentence is mild redundancy but earns its place by explaining what a README is; nothing is verbose.

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-value explanation is not required, and the tool is a simple two-param read. The only meaningful gap is the format/identity of graphId, which for a GraphOS tool with many graph-scoped siblings is a real risk.

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 0%, so the description must carry parameter meaning and largely does not. 'Provide the graph ID and the variant name' merely restates the two property names without specifying graphId format (slug, ID, ref) or clarifying that 'variant' is the variant name within that graph.

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 (read the README of a graph variant) plus the return contents (last-updated time and updater). It implicitly contrasts with the write counterpart PublishReadme in the sibling list but never names it, so differentiation is inferable rather than explicit.

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 rover CLI equivalence ('same read that `rover readme fetch` performs') anchors the operation for agents familiar with the CLI, and the closing line says what inputs to supply. However, there is no explicit when-to-use vs. when-not guidance, nor any pointer to PublishReadme for the write path.

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