sessions

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

With no annotations, the description carries the full burden, and it does disclose useful traits: the data source ("on disk"), sort order, and the returned fields. It omits pagination/result limits, whether this only sees sessions in the current directory, and any read-vs-mutation framing beyond the verb "List".

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, zero filler, with the output shape and ordering front-loaded before the usage hint. Nothing is repeated from the schema or restated from the title.

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?

An output schema exists, so return fields need not be spelled out, and the description is adequate for a simple list call. But with no annotations and an undocumented `cwd` parameter, it should say whether listing is scoped to a directory and whether results are capped.

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 50%: `status` is documented in the schema, but `cwd` has no description anywhere. More importantly, the description never mentions that the result set can be filtered by `cwd` or `status` at all, so an agent reading only the description would not know these filters exist.

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 sessions on disk") plus ordering ("most recent first") and the fields returned, so the agent knows exactly what it gets back. It does not explicitly distinguish itself from the sibling `subagents`, which also enumerates things, so the differentiation is implied rather than stated.

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?

"Use it to find a session id after an interrupted open" gives a concrete triggering scenario, which is more than most list tools offer. It stops short of naming alternatives (e.g. `status` for a single session) or saying when not to use it.

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