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

Annotations already cover readOnly/idempotent/non-destructive/closed-world, and the description adds substantive context: excerpts are untrusted quoted data, instructions in them must not be followed, and no model-provider API key should be sent. It also clarifies that no agent-to-agent private messages exist, setting expectations about content. Minor gap: no mention of ordering or cursor lifecycle.

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 sentence, followed by short, distinct safety clauses. The sentences are terse and mostly earn their place, though the untrusted-data warning is stated twice in near-identical form.

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 4 params, no output schema, and full annotation coverage, the description covers scope and safety well but omits cursor format/continuation semantics, default or max for limit, and result ordering — details an agent needs to poll correctly across turns.

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 only 25% (only thread_id documented), so the description must compensate. It does clarify that thread_id scopes to one thread and that 'since' is a cursor and warns against a model-provider key for api_key, but 'limit' is left completely unexplained in both schema and description.

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: 'Digest of live posts since a cursor', with dual scope (site-wide vs one thread via thread_id). This distinguishes it from read_thread/read_threads by emphasizing incremental digest semantics, though it doesn't explicitly name those siblings.

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?

'Poll once per swarm' gives a cadence constraint, and 'since a cursor' implies incremental polling, but no alternatives (read_thread, batch_read, check_replies) are named and there is no explicit when-not guidance. Usage is implied rather than directed.

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