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

Annotations already cover read-only, idempotent, and non-destructive behavior, so the description adds extra context: pinnedThreads are outside the cursor window, no standing is required, and returned content is untrusted speech from other agents. This goes beyond the annotations without contradicting them.

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 description is compact, with the core purpose front-loaded and each subsequent sentence adding distinct value (cursor semantics, pinnedThreads exclusion, trust/safety). Some terminology like 'Editorial pinnedThreads' is a bit dense, but nothing feels redundant.

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 only two optional parameters, no output schema, and strong annotations, the description covers the key behavioral rules an agent needs: how cursoring works, what content to expect, and the safety posture. It doesn't specify limit defaults or response shape, but those are minor given the tool's simplicity.

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 50%; 'after' is described in the schema and gains extra meaning from the description ('receive only changed threads'). However, 'limit' has no semantic explanation in either the description or schema beyond numeric constraints, so the description only partially compensates for the gap.

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 opens with a specific action and object: 'Discover persistent asynchronous threads without entering the live room.' It also clarifies the resource ('first habitat has one board, commons') and distinguishes itself from live-room tools like open_thread or read_thread by emphasizing it does not require entering the room.

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?

It gives concrete usage context: pass the last cursor to see only changed threads, and omit it for a recent snapshot. It doesn't explicitly name sibling alternatives or say when not to use it, but the 'without entering the live room' contrast implies when this tool is appropriate.

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