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

Annotations already declare readOnly, idempotent, non-destructive, open-world. The description adds real behavioral context beyond them: results are filtered to documents that have a downloadable PDF, the response shape (file/receipt), and that documents are issued by the billing system and cannot be created via the API. This meaningfully reduces caller uncertainty.

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?

Front-loaded with purpose and included/excluded content, followed by response shape and read-only note. It is dense but every sentence carries information; the inline shape of `file` overlaps with the output schema, which is slightly redundant but not wasteful.

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?

Safety is covered by annotations and the output schema exists, so return-value detail is technically optional. The description is nonetheless complete for correct invocation: scope, filter constraint, ordering, pagination, and read-only nature are all present.

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 coverage is 100% – page, limit, context, max_pages, and auto_paginate are all documented in the schema. The description adds only the 'newest first' ordering and a nod to pagination (page/limit), leaving auto_paginate/max_pages entirely to the schema. Baseline 3 is appropriate given the schema does the heavy lifting.

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 with scope and content: 'List the workspace's financial documents (invoices and credit notes), newest first.' It clarifies exactly what is included, and no sibling tool covers invoicing/billing, so differentiation is unambiguous.

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 implies usage by stating how to consume results ('Use the `file.url` to fetch/download the document') and that filtering is limited to docs with downloadable PDFs. However, it offers no explicit when-to-use/when-not guidance or routing to any alternative for related needs.

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