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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds the useful fact that the response bundles the list's contacts, but says nothing about how those contacts are paged or how large a list can be.

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?

Six words with zero padding, which is refreshingly terse, but the fragment is too thin to front-load any actionable information beyond the return content. Under-specification rather than genuine conciseness.

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 read tool with paging parameters and no output schema, the description should at least tell the agent that contacts come back paginated. Those two undocumented parameters and the missing pagination behavior leave a meaningful gap.

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 only 33%: 'id' is documented (pointing at list_lists) but 'page' and 'per_page' carry no descriptions. The tool description adds no parameter meaning at all, so it fails to compensate for the two unexplained pagination parameters (per_page max 50).

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 fragment "One saved list and its contacts" tells the agent it retrieves a single list plus associated contacts, which distinguishes it from the sibling list_lists (plural). However, it is a noun phrase rather than a stated verb+resource, and it never explicitly says it fetches by id.

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 guidance on when to use this versus list_lists (enumerate all lists), search_contacts, or get_contact. The only routing hint is indirect, via the schema's 'List id from list_lists.' reference.

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