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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds one genuine behavioral fact the annotations do not: results are permission-gated by the token, which tells the agent to expect partial or empty results rather than an error. It does not disclose what includeDeleted does or how permission failures manifest.

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, front-loaded with the returned resource and followed by the API/permission caveat. No filler, though the second sentence is slightly boilerplate.

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 two-parameter read tool with no output schema, the description usefully enumerates the returned fields (IDs, titles, references) and the API source. However, it omits the includeDeleted flag and any pagination or result-size behavior, leaving the agent without the full picture for invocation.

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 largely does not. 'For the requested sites' loosely hints at siteIds, but nothing explains that it is a UUID array capped at 100 items, and includeDeleted is never mentioned at all.

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?

Names the resource (account codes) and the fields returned (IDs, titles, references) plus the scoping to requested sites, so the agent knows exactly what entity this retrieves. It lacks a verb and any explicit differentiation from siblings like famly_list_sites or famly_get_invoices, but the resource is 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?

There is no statement of when to use this tool versus the sibling list/get tools, no prerequisites, and no exclusions. The only contextual sentence is a caveat about token permissions, which is not usage guidance.

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