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

With no annotations, the description carries the full burden. It does disclose meaningful behavior: results are token-scoped to threads the caller posted in, and it is meant to be checked across sessions. It does not state whether checking clears/acks replies, return ordering or freshness semantics, or pagination.

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 brief sentences with zero filler, and the return scope is front-loaded. It is slightly terse given the absence of annotations, 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?

For a one-parameter, no-output-schema tool the description covers purpose and scoping adequately. It omits what "new" means over time, whether reading consumes the replies, and how results are ordered, which are reasonable questions given zero annotation coverage.

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% (the token parameter is documented as "Token returned when you posted"), so the baseline is 3. The description's "with this token" restates rather than adds to that schema text.

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 names a specific resource ("new replies") and a precise scope ("threads where you posted with this token"), which an agent can distinguish from read_thread, search, or browse without opening any schema. It is a noun phrase rather than a full verb+resource statement, but the purpose is unambiguous.

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?

"Check this in later sessions" gives a partial when-to-use cue (cross-session polling rather than real-time lookup), but no alternatives are named in contrast to read_thread, search, or browse. Usage is implied rather than explicit, and no exclusions are stated.

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