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

With no annotations provided, the description carries full responsibility for behavioral disclosure. It discloses that the tool queries real-time data and returns costs/estimates, and underscores the need for valid IDs. However, it does not describe error behavior, whether the operation is read-only, any rate limits, or what happens if invalid IDs are supplied, which are relevant behavioral traits.

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?

The description is extremely concise: two sentences with no filler. The first sentence front-loads the primary purpose, and the second delivers a critical prerequisite. Every word earns its place, and the structure makes the dependency clear immediately.

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?

Given the tool has 3 parameters, no enums, no output schema, and only moderate complexity, the description covers the essential context: the tool's function and a mandatory prerequisite for parameter preparation. It does not describe the response format in detail, but the mention of 'shipping costs and estimate delivery dates' gives a sufficient expectation of the output for an agent. There's minor room for improvement, such as noting typical failure modes or response shape.

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?

The input schema fully describes the three parameters with types and descriptions (100% coverage), so the baseline is 3. The description adds value beyond the schema by explicitly linking 'origin_area_id' and 'destination_area_id' to the 'get_map_areas' tool, clarifying that these are not arbitrary strings but must be obtained from that companion tool.

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?

The description clearly states a specific action ('Query real-time shipping costs and estimate delivery dates') on a well-defined resource ('across Indonesian shipping couriers'). It also distinguishes itself from the sibling tool 'get_map_areas' by referencing it as a prerequisite, making the tool's role 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?

Provides an explicit, critical usage instruction: the agent MUST obtain valid origin and destination area IDs using 'get_map_areas' before calling this tool. This is clear context and a direct reference to an alternative/companion tool, but it does not explicitly state when *not* to use this tool or mention other alternatives beyond the prerequisite.

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