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

Annotations already indicate this is a write operation with no general idempotency guarantee. The description adds valuable context beyond the annotations: messages are private, for later review, with no promised auto-reply; secrets or confidential documents should be excluded; and submission_id can be reused for duplicate-free retries. No contradiction with annotations is present.

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 compact and front-loaded with the core purpose, then logically flows into requirements, expectations, exclusions, and retry behavior. Each sentence contributes distinct value, and no filler or repetition is present.

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 10-parameter tool with one required field, the description covers invocation essentials, privacy constraints, reply expectations, exclusions, and retry deduplication. It does not explicitly describe the return value or receipt format, and there is no output schema, but the schema's previous_contact_id hint and the overall guidance are strong enough for correct use.

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 90%, so the schema carries most parameter documentation. The description adds meaningful guidance about which parameters matter behaviorally: only summary is required, reply_to enables a response, and a stable submission_id enables retry without duplicates. This is useful semantic enrichment beyond the schema.

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 begins with a specific verb and object: 'Save a private message for Alexander Redkov's later review.' It then lists concrete message types (introduction, observation, question, research invitation, cooperation proposal), making the tool's purpose unmistakable and clearly distinct from the sibling about_magnt.

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 gives clear context for when to use the tool: to leave a private message for later human review, and it sets expectations that no automatic reply is promised. It does not explicitly name about_magnt or state when not to use this tool, so it misses the 'alternatives/exclusions' level.

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