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

The annotations already declare readOnly, idempotent, openWorld, and non-destructive behavior, so the bar is lower. The description adds genuinely valuable runtime context: the bare-array-to-wrapped-response behavior, that an empty result is normal, and that the tool's practical purpose is ID resolution. This goes beyond what annotations 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?

Every sentence earns its place: it names the resource, explains the response wrapping quirk, states there are no parameters, clarifies the empty case, and gives the intended use. It is compact while covering all necessary operational nuance.

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 zero-parameter, read-only list tool with an output schema, the description is complete. It covers what is returned, how it appears as an MCP result, the empty case, and how the tool should be used. Nothing an agent needs to invoke it correctly is missing.

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?

There are zero parameters and the schema is fully covered, so no parameter documentation is needed. The description correctly states 'Takes no parameters,' which matches the schema and removes any doubt about required inputs.

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 resource ('lists (labels) defined in this workspace') and the tool's role in resolving list names to IDs for filters. It does not explicitly name sibling tools to differentiate itself, but the resource is unambiguous among the many get_apollo_* siblings.

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?

It gives a concrete, actionable usage directive: 'Use it to resolve a list name into the id that contact and account filters expect.' It does not state when not to use the tool or mention alternatives, but the context is clear enough for an agent to decide.

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