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

Annotations already cover the read-only/idempotent safety profile, but the description adds auth requirements (login + organizer/admin), the returned content surface, and a real caveat that letter content only flows into export files and never appears on the public activity page — context the annotations cannot express.

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?

Three bracket-labeled lines, each front-loaded and carrying a distinct payload (what it returns, the workflow chain, the data-visibility pitfall). No filler; every clause earns its place.

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 only one parameter, the description carries the full burden of explaining return content and does so, plus access control, workflow position, and a visibility caveat. Nothing an agent needs to call it correctly is missing.

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% and the single 'activity' param is fully documented in the schema (id or slug, with source tools named). The description adds no syntax or format detail beyond that, so 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?

Clear verb+resource: it reads an activity's invitation letter, and it enumerates exactly what comes back (current style, possible formats, written-in blocks, addable blocks, tips, contact). It explicitly distinguishes itself from the sibling tools update_activity_letter and render_activity_letter by placing itself in a get→update→render chain.

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?

It states the access precondition (login required; organizer/admin only) and its position in the workflow chain, naming the downstream siblings explicitly. An agent knows both when to call it and what to do next.

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