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

Annotations already declare readOnly/not-destructive, so "Changes nothing" is largely redundant. The genuinely additive detail is "a tool call gets the link, the CLI saves the file", which explains that the tool must be paired with client-side writing - behavior not visible in 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?

Two compact sentences, front-loaded with the action and scope. Slight redundancy in "Changes nothing" against the readOnlyHint annotation, but nothing wasted overall.

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 no output schema, the description usefully explains the return path (link retrieved, PDF saved by CLI). For a simple three-param read tool with full annotation coverage, that is close to complete; permission/authorization context is only implied.

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 all three parameters (id, output, business) are already documented in the schema. The description adds a marginal hint that the file is saved by the CLI, aligning with the `output` path parameter, but no extra semantics beyond that.

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 (Download) plus resource (receipt PDF) and a precondition (paid invoice). It is clearly distinguishable from the sibling agenta_invoices_send_receipt, which sends rather than downloads.

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?

"For a paid invoice" implies the eligible state for use, but no when-not conditions or alternatives (e.g. send_receipt, list) are named. Usage is implied rather than explicitly routed.

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