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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds real behavioral context beyond that: a cost model ('Free within the per-IP allowance, then $0.002'), a freshness guarantee ('Live data only'), and the fact that the prompt is surfaced in full pre-execution. It could go further on what the returned prompt contains, but it is substantially richer than the 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 step number and the resource are front-loaded, and the workflow/pricing sentences follow in a sensible order. It is slightly dense with stacked parentheticals, but every sentence conveys a distinct fact (workflow, editability, cost) with no filler.

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 structure need not be explained, and the description covers sequencing, editability, next calls, cost, and data freshness. For a two-parameter read tool with full schema coverage, this is close to complete; only the scheme/format expectations of a 'route URL' go unmentioned.

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 100%, so both parameters are already documented in the schema. The description restates the routes cardinality rule ('one route resells it, two to five bundle them') but adds no syntax or format detail beyond the schema, and budget is not addressed at all. Baseline 3 for a schema that carries the semantics.

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 names a specific resource — the default planning prompt for the chosen x402 pathway — and its scope ('shown in full before anything runs, with the compute terms'). The verb is implied rather than stated ('shown in full'), but an agent can tell this retrieves/renders a prompt rather than executing a run. It is clearly distinct from pathways_run and pathways_authorize by naming them.

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?

It explicitly positions itself in a sequence ('Step 3 of Open Commerce Pathways'), states the action to take on the result ('Edit it if you like'), and names the exact follow-up calls in order ('authorize one run with pathways_authorize, then call pathways_run'). That is an explicit when-and-what-next with named alternatives.

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