get-numberGet information about a specific fax number.
Side effects: none (read-only).
| Name | Required | Description | Default |
|---|---|---|---|
| number | Yes | Fax number in E.164 form, e.g. +1234567890. | |
| user_id | No | Fax.Plus user ID. Default: self. |
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | ||
| number | Yes | ||
| status | Yes | ||
| owner_id | Yes | ||
| assigned_to | Yes | ||
| is_canceled | No | ||
| acquired_date | Yes | ||
| notifications | No | ||
| expiration_date | No |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description repeats the read-only behavior already declared by annotations (readOnlyHint=true, destructiveHint=false) without adding any new behavioral context. It does not disclose response characteristics, authorization needs, or other constraints beyond what annotations and schema already provide.
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 first sentence is direct and front-loaded. However, the second sentence merely restates annotation data, so it does not earn its place; the description is short but slightly redundant given the available annotations.
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 simple read-only retrieval tool, the description, fully documented schema, and presence of an output schema give an agent enough to select and invoke it correctly. It lacks alternative-routing guidance, but that gap is minor for a one-resource lookup.
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 already provides full descriptions for both parameters, including the E.164 format for 'number' and the default for 'user_id'. Since schema coverage is 100%, the description does not need to add parameter detail and offers none.
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 identifies the operation: retrieving information about a single fax number. The qualifier 'specific' distinguishes it from list-oriented siblings like list-numbers and from mutating tools like purchase-number or revoke-number.
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?
No explicit when-to-use or when-not-to-use guidance is provided. The phrase 'specific fax number' implies use for a single-number lookup rather than a list operation, but the description does not name alternatives or exclusion conditions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.