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

Goes beyond the annotations by disclosing the approval precondition (confirmed_by_user=true), the rate limit, and the duplicate-suppression behavior. This adds real operational context on top of openWorldHint/idempotentHint, letting the agent anticipate failure modes rather than infer them.

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 English content is front-loaded and tight, but the appended Russian sentence restates the same information, which is redundant for an agent consuming the tool. The duplication wastes space without adding meaning.

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 5 fully-documented parameters, the description still covers everything an agent needs: the approval gate, idempotency, and rate limiting. Nothing material is missing for successful invocation.

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%, so the baseline is 3. The description confirms that the approved email is the reply-to address, but adds little syntax or constraint detail beyond the already-documented schema fields.

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?

States a specific verb and resource ('Delivers a message to Andrey Zubar') and pins down the mechanism ('same mechanism as the contact form on the home page'). All nine siblings are read-only getters/listers, so this write-to-owner tool is unmistakable.

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?

Gives clear context: it requires prior human approval of the exact text and reply-to email, and notes it is rate limited with duplicate suppression. It does not explicitly name alternatives, but no sibling performs a comparable action, so the omission is minor.

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