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

Description contradicts annotations. Annotations declare readOnlyHint: true and idempotentHint: true, but the description states 'Set mark_read:true to flag returned events read so the next call only shows newer ones,' which is a state-changing, non-idempotent operation. This is a direct contradiction, so the score must be 1.

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?

The description is three sentences, front-loaded with the core action, then details return fields, filtering, and mark_read semantics. Every sentence adds value with no redundancy or 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?

For a tool with no output schema, the description explains return fields (source, citation_uri, raw payload), filtering options, mark_read behavior, and even alternative access. It lacks error/edge-case details, but overall it is sufficiently complete for a read-like tool. The annotation contradiction is covered elsewhere.

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% with per-parameter descriptions. The description adds extra meaning by explaining mark_read's effect ('so the next call only shows newer ones') and framing type/since as combinable filters with an example. This goes beyond the schema's basic descriptions, justifying a score above baseline.

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 clearly states the tool's purpose: 'Pull fired events from your subscription feed.' It specifies the resource (alerts on the persisted feed) and the return content (source, citation_uri, raw event payload), distinguishing it from siblings like list_subscriptions or recent_changes.

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?

The description provides useful context: filtering by type and since, marking events read, and notes that polling works fine. It even mentions an alternative access method (the HTTP feed for scripts/dashboards). However, it does not explicitly state when to prefer this tool over siblings or when not to use it, so it falls short of a 5.

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