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

No annotations are provided, so the description must carry the full behavioral burden. It does disclose one genuinely useful behavior that is not in the schema: if no dates are given, the data covers the last 7 days. Beyond that, it says nothing about the read-only nature, rate limits, or result ordering, so it supplies some but not rich behavioral context.

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?

Two sentences, with no filler. The identity of the data returned comes first, and the non-obvious default-window rule follows, which is front-loaded where the agent will see it.

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 read-only reporting tool with a full output schema and 100% parameter coverage, the description covers the essentials: what is returned and the default date behavior. It only lacks differentiation from the many other Metrika report siblings, which is the one thing an agent must resolve before calling this tool.

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 parameters are already well documented and the baseline is 3. The description adds only one semantic detail beyond the schema: the default behavior of date_from and date_to. It says nothing about how sort, limit, exclude_robots, or new_users_only affect the result.

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 states a specific verb and resource: retrieve session and user counts from search engines in Yandex.Metrika, with optional filters. That is far more specific than a tautology. It does not, however, differentiate this tool from close siblings such as get_metrika_sources_summary or get_metrika_visits, so the agent must infer which report fits.

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 phrase 'with optional filters' implies that the tool is for filtered reporting, but there is no explicit statement of when to use this tool rather than get_metrika_sources_summary, get_metrika_visits, or get_metrika_data_by_time. Usage is therefore only inferable from the report's scope; no exclusions or alternatives are given.

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