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

Annotations declare destructiveHint=true, openWorldHint=true and readOnlyHint=false, yet the description's sole verb, "Model", reads as harmless analysis. Nothing warns that data leaves the boundary (the schema requires consentExternalProcessing) or that a payment invoice (paymentInvoiceId) may be involved — that is precisely the context the annotations cannot convey in prose and the agent needs before invoking.

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?

One clause, front-loaded with the verb and the concrete artefacts produced, with zero filler. The problem is coverage, not bloat — every word present earns its place.

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 tool with a nested six-field input object, required explicit external-processing consent, an idempotency key and a destructive annotation, one sentence is far short. With no output schema, the description also owes the agent some notion of what comes back (summary, financial model, supplier-pushback findings).

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 67% and the schema already documents apData's CSV shape, dpoTarget examples and constraints guidance, so the description need only fill residual gaps. It fills none: no mention of dpoTarget formats, costOfCapitalPercent, the optional dynamicDiscount hurdle rate, or how sourceRunIds/sourceFields chain prior runs.

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?

Specific verb ("Model") plus three concrete outputs — payment-term changes, working-capital impact, supplier pushback — grounded in a named input (AP data). It is clearly a modelling/analysis tool rather than a document fetcher, but it never differentiates itself from near-neighbours like xnegotiate-coach or xspend-taxonomy, so the agent must guess on that axis.

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?

There is no when-to-use, when-not-to-use, or named alternative anywhere in the sentence. Nothing tells the agent whether this is the right tool for a supplier-negotiation question versus a spend-taxonomy or negotiation-coaching question in the sibling list.

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