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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description adds meaningful boundaries instead — that sending, editing, buying letters and uploading contacts are impossible through the assistant, and why (mail goes to live people and cannot be recalled). This is real context beyond the annotations, though the reason given is somewhat rhetorical.

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?

Front-loaded with the resource and its parts, then boundaries. It is somewhat long, but each sentence carries distinct information (scope, section routing, quiz-email exclusion, read-only/impossibility constraints, file-upload exclusion) rather than padding.

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 multi-section reader with no output schema, the description plus the section enum's own documentation cover what each call returns, how to bootstrap (campaigns then contact_lists) and what is out of scope. Safety is handled by annotations, so nothing critical 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%, so the schema already documents every parameter (including per-section requirements and enum meanings). The description only points at section ('там же сказано, какой раздел чего требует') without adding format or semantics the schema lacks, so the 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?

States a specific resource (e-mail campaigns of the account) and enumerates exactly what it exposes (campaigns and metrics, recipients and their outcomes, lists, templates, reputation, balance, settings, SMTP log) gated by the section argument. It also explicitly draws the boundary with get_quiz_email_settings and neighbouring tools, so an agent can tell it apart from siblings without opening a schema.

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 for use and even an ordering hint ('Начинайте с campaigns' since campaign IDs come from there), plus names the alternative tool for quiz-triggered emails. It stops short of fully spelling out when-not-to-use-more-broadly, but the routing advice is concrete rather than implied.

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