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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered and the description need not restate it. The description adds genuine value by disclosing what is returned: 'complete text', 'exact change', and 'UTC recorded_at' timestamp format, plus the immutability property. No contradiction with 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?

A single sentence with zero filler. The core purpose ('Read one immutable revision') is front-loaded, followed by the output specifics. Every word earns its place; no redundancy with the annotations or schema.

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 2-parameter, read-only tool with a present output schema and annotations covering the safety profile, the description is nearly complete. It communicates the scope (immutable revision), the content returned (text, change, UTC timestamp), and the read-only nature. The only gap is the lack of explicit when-to-use guidance, which is a minor omission for such a straightforward tool.

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 carries the burden of explaining the parameters. It clarifies the domain (reading a revision) and the output semantics but does not explicitly define what 'key' (a 64-char hex identifier) or 'revision' (an integer) refer to beyond the schema's own pattern and range constraints. It partially compensates for the coverage gap but stops short of fully explaining the parameters.

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 states a specific verb ('Read'), a resource ('one immutable revision'), and the payload ('complete text, exact change and UTC recorded_at'). The word 'immutable' plus 'saved revision' clearly differentiates it from the sibling 'read' tool (presumably the current document state) and from 'events' (a history listing). An agent can distinguish it from siblings without opening the schema.

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 description conveys that this reads a specific historical revision rather than the current document, which implies a contrast with the sibling 'read' tool. However, it never explicitly states when to choose this over alternatives or names any exclusion ('use read for the live document, events for the list'). The usage context is implied by the word 'immutable' but not stated.

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