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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description earns credit by disclosing what each returned arc actually contains (entities, related question count, cross-domain mention volume, first/last-seen dates) — genuinely valuable since there is no output schema. It says nothing about ordering or pagination behavior beyond what the schema already states.

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 sentences, front-loaded with the resource and its return shape before the optional filter note. The em-dash clause is dense but each element (entities, question count, mention volume, dates) adds information rather than filler.

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 no output schema and zero required parameters, the description correctly carries the return-value burden and does so explicitly. It is only missing behavioral details an agent might want — result ordering, what happens when query matches nothing, or how it differs from the other entity/topic read tools.

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%, so both parameters are already documented (limit with default 20 / max 50, query as name-or-entity filter). The description's 'query filters by name or entity' only paraphrases the schema and omits any mention of limit. Baseline 3 is the right call when the schema does the heavy lifting.

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 gives a specific verb-and-resource ('Tracked world events... the engine follows as named arcs') and enumerates the concrete payload: entities, market-question count, mention volume, first/last-seen dates. That is far more than a restatement of the name. It falls short of a 5 only because it never distinguishes itself from adjacent readers like get_entity, search_entities, or get_topic_record.

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?

'Optional query filters by name or entity' implies the usage pattern (list all arcs, or narrow to one), which is the correct mental model. However there is no explicit when-to-use or when-not-to-use guidance, and no routing to sibling retrieval tools such as get_entity or search_entities when the agent wants an entity rather than an arc.

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