list_actors

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

No annotations are provided, so the description carries the burden. The 'List' verb signals a read-only, side-effect-free operation, and it proactively discloses filtering behavior by naming what is excluded (private and ToS-blocked actors) -- a genuinely useful behavioral trait. It does not address auth requirements, result size, or pagination, which keeps it short of a 5.

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?

Three short sentences, front-loaded with the core action, followed by the return shape and then the exclusion caveat. No sentence is wasted and the most important information comes first.

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 discovery tool, the description covers what is returned and what is deliberately omitted, and an output schema exists to carry the exact return structure. Nothing an agent needs in order to call 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?

The tool takes zero parameters, which is the baseline-4 case. There is nothing for the description to clarify beyond confirming the call is argument-free, and the schema reflects that.

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 a specific verb and resource ('List all public TinyRex Apify Store actors') with scope qualifiers that tie it to run_actor's capability set ('this MCP can run'). An agent immediately understands this is the enumeration/discovery tool, clearly distinct from run_actor.

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?

Usage is implied rather than stated: it enumerates exactly the actors run_actor can execute, but the description never says 'call this first to discover valid inputs for run_actor' or notes any preconditions. The exclusion clause ('Private / ToS-blocked actors are not included') is helpful context but is not routing guidance.

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