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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the bar is lower. The description still adds a genuinely non-obvious trait: fetching this thread has no read-receipt side effect, which is exactly the kind of detail annotations cannot convey. It does not describe ordering or pagination of the thread, keeping it from 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, zero filler, with the core action front-loaded and the routing guidance immediately after. Every sentence carries distinct information (what it does, where to go next, side-effect note).

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 an output schema present, the description needn't explain return values, and annotations cover the safety profile. The only residual gap is that 'primary thread' is never characterized (e.g., whether it is the root of a threaded conversation), which is a minor but real omission for a get tool.

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 100%, and the single space_id parameter already documents its format and the 'omit if sole' default behavior. The description adds nothing about the parameter, so the baseline 3 applies rather than a higher score.

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 concrete verb and resource: 'Find the Space's primary thread', which is more specific than the tool name alone and lets an agent tell it apart from the list_* conversation siblings. The verb 'Find' is slightly softer than the 'get' in the name, and it never says what a 'primary thread' object actually represents, so it falls just short of a 5.

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?

Explicitly routes the agent: use swarm_list_conversation_entries for text and swarm_list_conversation_anchors for links. Combined with 'Nothing is marked read', it also implicitly points at swarm_mark_thread_read for the read-state mutation, leaving no ambiguity about which sibling handles what.

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