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

readOnlyHint=true already covers the safety profile, and the description usefully adds the ordering guarantee ("newest first"). However it says nothing about result truncation, default page size, or what happens past the 50-item maximum — meaningful behavioral gaps for a list tool.

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 short sentences, front-loaded with the resource and ordering before the optional filter. Slight redundancy in re-listing the enum values that the schema already defines.

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?

Adequate for a simple two-parameter read tool, but with no output schema the agent gets no hint of the return shape, and the undocumented limit parameter plus absent pagination/truncation notes leave real gaps for a list operation.

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 0%, so the description must carry parameter meaning, but it only restates the status enum values already present in the schema and never mentions the limit parameter at all. Default (20) and maximum (50) are left entirely to the agent to discover in the raw schema.

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 your Billify invoices") plus a scope detail ("newest first"). It distinguishes a list operation from siblings like get_invoice, though it never names a sibling explicitly.

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?

"Optionally filter by status" implies when the status filter is useful but gives no explicit when-to-use vs when-to-use-an-alternative guidance. Nothing tells the agent when to prefer get_invoice or when listing is the wrong approach.

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