agent_list

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

There are no annotations, so the description carries the full behavioral burden. It discloses the return payload (harness, state, cwd, screen preview) and implies a read-only enumeration, but says nothing about permissions, cost, truncation of the screen previews, or large-result behavior for a machine-wide scan.

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 sentences, front-loaded with the verb and resource, and the second sentence supplies the highest-value routing advice. The first sentence is somewhat clause-heavy, but no sentence 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, the description responsibly names the returned fields, and all three optional parameters are documented in the schema. What is missing is only marginal: the effect of the json flag and any note on the size or sensitivity of screen previews.

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 coverage is 100% with descriptions and enums on kind and harness, so the schema already does the work; baseline 3 applies. The description adds no filter semantics and in fact mentions 'harness' only as a returned field, which arguably blurs rather than clarifies the harness filter parameter.

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 with scope ('List every agent session on this machine in one view') and enumerates what is returned (harness, state, cwd, screen preview). It is clear on its own, but it never differentiates itself from the similarly named sibling agent_inventory, which an agent could easily mistake for the same job.

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?

'Call this first — every other tool takes an id or name from here' gives explicit workflow context and explains why an agent would invoke it before others. It stops short of any exclusion or comparison, so it does not say when agent_inventory or the filtered siblings would be preferred instead.

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