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

Annotations already declare readOnlyHint=true, so the safe-read nature is covered. The description adds useful behavioral context beyond this: newest-first ordering, included statuses and timestamps, and the critical prerequisite that session_id must include the ?token=... suffix and be passed exactly. The credential-handling emphasis is especially valuable, as it prevents a common caller error.

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 tightly structured in four short sentences: main action, output highlights, use cases, and a required-parameter note. Every sentence earns its place, and the most critical information is front-loaded in the first sentence. No fluff or redundant phrasing.

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?

Despite having no output schema, the description explicitly lists the core returned fields: version number, status (draft/confirmed/applied), change summaries, and timestamps. It also includes the necessary input prerequisite and intended usage. For a read-only list tool with one parameter, this gives an agent enough context to invoke it correctly and interpret the result.

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 100%, and the schema's session_id description is already extremely detailed—including the exact format, token suffix, and instruction never to strip it. The description merely repeats 'REQUIRES: session_id from convoopen response (format: sess_v2_...)' without adding new meaning beyond the schema. Therefore, a baseline score of 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 and resource: 'List all stack versions for a session (newest first).' It clearly differentiates this tool from siblings like stackdiff or stackrollback by focusing on version history listing. The output contents and ordering are explicitly stated, leaving no ambiguity about the tool's function.

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 provides clear when-to-use guidance: 'see the design history, review what changed between iterations, or find a version number to roll back to.' It does not explicitly name exclusions or alternatives (e.g., stackrollback for actual rollback), but the use cases are well-defined and align with the tool's purpose.

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