list_harnesses

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

With no annotations, the description carries the full burden and does so well: it discloses what is included (runnable harnesses, non-runnable ones with reasons, server limits) and a meaningful exclusion rule (built-in harnesses that are not installed are omitted). It does not state that it is a read-only/safe operation, which leaves a small gap.

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 purpose is front-loaded and every clause carries distinct information (content types, failure reasons, server limits, exclusion rule). The first sentence is dense and slightly run-on, but nothing is wasted.

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?

With no output schema and no annotations, the description compensates by enumerating the shape of the returned content and the exclusion criteria. An agent has enough to decide when to call it and what to expect back.

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, so the schema has nothing to document and the description correctly adds no parameter information. Baseline for a zero-param tool is 4.

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 uses a specific verb+resource ('List valid agent values ... installed harnesses with their models and effort levels') and explicitly ties itself to run_thronglet, which distinguishes it from list_thronglets and the other siblings. An agent can tell exactly what this tool returns without opening any schema.

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?

By stating it lists 'valid agent values for run_thronglet,' the description makes the intended call context clear: consult this before invoking run_thronglet. It does not spell out explicit when-not-to-use conditions or non-obvious prerequisites, so it falls short of a 5.

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