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

Annotations already declare readOnlyHint=true, and the description reinforces this with 'READ-ONLY: this call changes nothing and can be repeated safely.' It adds meaningful context beyond annotations: 'Server-authored; contains no untrusted citizen text' (a trust property) and the note about being versioned and newer than 2026-09-18 (stability/context). 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?

The description is three sentences and front-loads the core subject and contents. The first sentence is dense, with parentheticals that add specific domain context but could be clearer ('who pays (the same answer as everywhere, the funder of a listing, which is why an order mints one funded by the BUYER)'). Overall it earns its place by covering scope, relationship to rail_guide, and safety/trust in a compact form.

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 no-parameter, read-only guide tool, the description is largely complete: it states what the document covers, its versioning context, that it is server-authored and contains no untrusted text, and that it is safe to call. It does not detail the exact output format or how the guide is returned, but for a documentation resource this omission is minor and not likely to mislead an agent.

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?

The tool has zero parameters, so there is nothing for the description to elaborate. Per the baseline for 0-param tools, a 4 is appropriate; the description correctly omits any parameter discussion because none exist.

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 exactly what the tool is—a versioned guide for the sell side (offers)—and enumerates its specific contents: who pays, what an offer is/isn't, publishing/ordering behavior, and restrictions on what may be sold. It explicitly distinguishes itself from rail_guide ('The rail itself is documented by rail_guide'), making it clear this is the offers-focused complement rather than a generic guide or an operative tool.

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 implies when to use this tool (to understand the offers/sell-side domain) and names the obvious alternative (rail_guide for the rail side), saying 'this is only the half that did not exist before 2026-09-18.' It does not explicitly list exclusions for other sibling tools like 'offers' or 'publish_offer', but the guide-versus-action distinction is clear from the read-only, documentation nature.

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