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

Annotations already establish the read-only, idempotent, non-destructive profile. The description adds valuable context beyond that: it warns that mark_read:true 'flag[s] returned events read' so the next call only shows newer ones, and it discloses the return structure (source, citation_uri, raw event payload). This is a helpful disclosure of a subtle state-changing side effect.

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 five sentences, all dense with functional information. It front-loads the primary purpose, then proceeds logically to return format, filtering, side-effect flag, and alternative access. No filler or redundancy.

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, this description covers the return payload, filtering options, a state-changing parameter, and an alternative access method. It gives the agent enough to invoke and interpret the tool correctly without additional documentation.

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?

With 100% schema coverage, the baseline is 3, but the description adds meaningful detail: it gives a concrete example for type ('sec_8k'), specifies the format for since ('ISO timestamp'), and explains the behavioral consequence of mark_read. It does not elaborate on limit or unread_only, but the schema already covers those clearly.

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 opens with a specific verb+resource: 'Pull fired events from your subscription feed.' It further clarifies the scope ('most recent alerts the evaluator has written to your persisted feed') and lists the content of each alert, making it distinct from sibling tools 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 clear context for when to use the tool ('Filter by type and/or since', 'Polls work fine') and even mentions an alternative HTTP endpoint for scripts/dashboards. However, it does not explicitly reference sibling tools or state when not to use this tool, so it stops short of full exclusions.

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