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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuinely new behavioral detail beyond them: the default (50) and maximum (200) result cap, newest-first ordering, and the false-negative trap. That is exactly the context an agent needs and cannot get from the annotations or schema.

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 tight sentences, front-loaded with the core action and then the essential caveat. Every clause earns its place; nothing is redundant.

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 no-output-schema search tool, it covers the decisive behavioral facts (cap, ordering, false-negative avoidance). It is slightly incomplete on the undocumented filter parameters and their accepted formats, but the practical guidance is strong.

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 0%, so the description must carry the load. It usefully documents limit (default 50, max 200) and names invoice_number, min_total/max_total, and date_to, but leaves status, date_from, po_number, and vendor_id — half the parameters — completely unexplained, including any accepted values or formats.

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 clear verb+resource ("Search invoices") that an agent can act on immediately. It does not explicitly differentiate from siblings like search_pos or search_vendors, though the resource name makes the scope self-evident.

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 actionable guidance: all filters are optional, omit unneeded ones, and — critically — raise the limit or add filters before concluding something does not exist. This directly addresses a real failure mode. It stops short of naming alternative sibling tools for related lookups.

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