get_number

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

With no annotations, the description carries the full burden of behavioral disclosure. It explains that the tool returns either the full payload or a subset via `fields`, which is a useful behavioral detail beyond the schema. It does not mention side effects or permissions, but since this is a read operation, the disclosed behavior is sufficient for typical use.

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 two sentences long, front-loaded with the primary purpose, and provides a focused example. Every sentence earns its place without redundancy or unnecessary detail.

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 output schema exists (so return values are already documented) and the tool is a simple single-resource getter, the description covers the main behavioral nuance (partial payload selection). It does not mention prerequisites beyond the required parameters, but the schema already lists those. The description is complete enough for a tool of this complexity.

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 compensate for the lack of parameter documentation. It thoroughly explains `fields` but provides no additional meaning for `number_id` or `account_id` beyond their self-evident names. This partial compensation is insufficient for a low-coverage 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?

The description clearly states the tool retrieves 'full details for a specific tracking number,' using a specific verb and resource. It distinguishes itself from sibling get_ tools by explicitly naming the resource type (tracking number), so the agent knows exactly what this tool accesses.

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 description provides explicit guidance on using the `fields` parameter to reduce payload, including a concrete use case ('when checking several numbers in a row'). However, it does not mention any alternatives or when not to use this tool, so it misses the full picture of exclusionary guidance.

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