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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered structurally. The description adds genuinely new behavioral context — that Xenition cannot send communications, and that only ledger-resident invoices are reachable — but says nothing about pagination, result caps, or ordering.

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?

Three sentences, each load-bearing: capability first, filters second, routing guardrails third. The critical negative constraints are stated directly rather than buried.

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?

With an output schema present, return values need not be described, and annotations plus the description together cover safety, scope, and trigger conditions for a zero-required-parameter read tool. Nothing an agent needs to call it correctly is missing.

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% with only two optional parameters, so the baseline is 3. The description's 'filter to a vendor or only unpaid ones' simply restates what the schema already documents and adds no syntax, matching, or case-sensitivity detail.

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?

States a specific verb and resource ('List ... Xenition ledger invoices') plus the returned attribute (paid/unpaid status), which is enough to separate it from siblings like add_ledger_entry and mark_paid without opening any 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?

Gives explicit positive triggers with sample utterances ('what invoices are unpaid', 'how much do I owe vendor X') and explicit exclusions: not for sending/delivering invoices, and not for invoices outside the user's ledger. Nothing is left to inference.

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