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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so the safety profile is covered; the description adds genuinely new context: daily-collected observatory data, default 7-day window, and pagination via limit/offset. 'No side effects' partly restates annotations, which keeps it from a 5.

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?

Default behavior is front-loaded, then mode selection, then usage routing — a sensible order with no filler sentences. The long compound opening clause is dense and slightly run-on, costing a point.

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 zero-required-param list tool with an output schema and read-only annotations, nothing needed to call it correctly is missing: window, mode switch, pagination, and freshness are all stated.

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 0%, so the description must carry the load, and it does explain the semantics of four of five params: event_type/canonical_key switch to the full feed, since=YYYY-MM-DD widens the window, limit/offset page. It never says what event_type values are valid or what canonical_key format looks like, so the gap is not fully closed.

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?

Names a specific verb and resource (list tracked ecosystem events) and spells out the two distinct operating modes: unfiltered gives per-type counts over 7 days plus latest event and a legend, filtered gives the full feed. An agent can separate it from the many get_*_summary siblings without opening a schema.

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?

Gives an explicit trigger ('Use when the user asks what changed recently in the ecosystem') and an explicit alternative ('For counts rather than the feed use the `get_*_summary` tools'). It also states which parameters select which mode.

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