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

Annotations cover readOnly=false, idempotent=false, destructive=false, but the description adds genuinely new behavioral context: skipped messages remain readable via list_messages, and out-of-range to_seq returns 400. It does repeat 'not idempotent' from annotations, but that is harmless and the error/forward-only detail is value beyond structured fields.

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?

Purpose is front-loaded in the first clause and every fragment adds information, though the first sentence is dense with multiple clauses. No filler, but slightly packed.

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 single-parameter cursor-mutation tool with no output schema, the description covers intent, effect on unread state, where skipped messages go, failure behavior, and idempotency — everything an agent needs to call it correctly.

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% and documents to_seq as 'default the latest, forward only', so the baseline is 3. The description adds error semantics (behind cursor or past latest fails 400), giving meaningful extra meaning about valid values.

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 ('Move your unread cursor forward') and immediately differentiates from siblings by naming catch_me_up, receive_unread_messages, and list_messages with the effect on each.

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 says when to use it (after catch_me_up, which does not move the cursor) and what alternative exists for reading skipped messages (list_messages). The forward-only limitation is spelled out with the failure condition.

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