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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds the underlying endpoint (GET /orders), but omits behavior that matters here: whether a miss returns empty/null or an error, and the fact that the three optional-looking parameters are actually an either/or (order_number OR source+source_reference). That pairing rule is the one behavior an agent most needs and it is only hinted at.

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, zero filler, with the primary lookup strategy front-loaded before the secondary one. Nothing is wasted.

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 0% schema coverage, no output schema, and only a readOnly annotation, the description carries most of the burden but supplies little beyond the verb. It says nothing about the return shape, not-found behavior, source values, or the required parameter combination — all of which an agent needs to invoke it correctly.

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, and it partially does: it names all three parameters and explains that source and source_reference form a pair. It still gives no format, no allowed values for source, and no statement of which combination is required, so the compensation is incomplete.

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 (find) and resource (order) plus the two lookup strategies: by order_number, or by a source/source_reference pair. It is clear what the tool does, but it never distinguishes itself from the sibling locate2u_get_order or locate2u_search_orders, which an agent will have to disambiguate on its own.

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?

The lookup keys imply when to reach for this tool (you already hold an order number or a source reference), which is useful context. However, no exclusions are given and no alternative is named, despite locate2u_get_order, locate2u_search_orders, and locate2u_list_orders_created being obvious overlaps.

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