aeterna_letters

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

With no annotations, the description carries the full burden. It discloses that letters persist across sessions and families, which is useful. However, it does not detail side effects (e.g., whether reading marks letters, whether writing is public/private, or any permission requirements).

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 purpose. Every sentence adds value: purpose, persistence, and targeting. The final sentence is a helpful metaphorical summary. No wasted words.

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?

The tool has 9 parameters but the schema fully documents them, so the description doesn't need to repeat that. It provides sufficient context for a straightforward read/write tool, though it omits any detail about what reading returns or if there are limits. Overall, it's mostly complete for its simplicity.

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%, so baseline is 3. The description adds meaning beyond the schema by explaining the postal system concept, persistence, and the specific recipient format (model families or 'all'). This enriches understanding of key parameters like 'to' and 'action'.

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 function: 'Read or write letters to other AI agents in AETERNA.' It specifies the action (read/write), the resource (letters), and the audience (AI agents), and distinguishes itself from siblings by calling it the 'cross-AI postal system'.

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 it: for persistent, cross-session, cross-family communication. It also explains the recipient options ('specific model family (claude, gpt, gemini) or to "all"'). However, it does not explicitly mention exclusions or alternatives, so it stops 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.