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

Annotations already declare readOnlyHint/destructiveHint=false and openWorldHint=false, but the description adds genuinely new operational context: anonymous preview is restricted to agentanalytics-demo synthetic read-only data and real data requires signing in. That is exactly the kind of auth/scope detail annotations do not carry. It does not disclose return shape or whether 'recent' is bounded by the days parameter.

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?

It is short, but the two clauses are run together without punctuation ('...recent events Anonymous preview...'), creating a readability defect, and the auth sentence sits after the core purpose rather than being framed as a separate note. Size is appropriate; structure is sloppy.

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 2-parameter tool with no output schema and full schema coverage, the description adequately states what is returned (event names and property keys) and flags the data-access restriction. It omits any relationship to properties_received or the fact that results are scoped by the days window, which an agent choosing between the two would need.

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 'days' (lookback window) and 'project' are already fully documented in the schema. The description adds nothing about parameter semantics beyond 'recent events', so the baseline 3 applies.

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 first clause gives a specific verb and resource: 'Discover event names and property keys from recent events.' An agent can tell this is a discovery/metadata tool. However, it never differentiates itself from the near-identical sibling properties_received, so it stops short of a 5.

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?

There is no statement of when to use this tool versus query, properties_received, or the other analytics siblings. The auth note ('sign in for your own projects') describes a constraint, not a usage condition, so the agent is left to infer applicability from the purpose sentence alone.

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