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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds useful context by enumerating the returned attributes and naming the endpoint, which matters because there is no output schema; it still omits not-found/error behavior.

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 compact and front-loaded: it identifies the tool as fetching one fax by id, then lists the payload fields, then gives the endpoint. Every clause carries useful information and there is no filler.

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 one-parameter read operation with annotations and full schema coverage, the description is mostly complete: it explains the resource, returned fields, and endpoint. It could be stronger by mentioning not-found behavior or confirming that all listed fields are always present.

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 100%, and the single fax_id parameter is documented as coming from placetel_list_faxes. The description adds only the phrase 'by id' and no additional format or constraint details beyond the schema, so the baseline of 3 applies.

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 the resource and scope precisely: one fax by id, plus the fields returned and the underlying GET endpoint. It is clearly distinguishable from placetel_list_faxes by the 'one fax by id' framing, though it does not explicitly name the sibling alternative.

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 implies usage when a specific fax id is known, and the schema points to placetel_list_faxes as the id source. However, the description itself gives no explicit when-to-use guidance, prerequisites, or alternative-tool routing.

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