query_explain

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

With no annotations provided, the description carries the full behavioral burden. It does convey that the tool returns a plan and cost rather than query results, and it implies a pre-check role. However, it does not explicitly state whether the query is executed, whether the operation is read-only, or what side effects may occur. No contradiction exists with annotations because there are none.

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 concise and front-loaded: the first sentence states the core purpose, and the second gives a practical use case. The trailing '(фича G)' is minor noise that does not help an agent invoke the tool, preventing a perfect score.

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?

An output schema exists, so return values do not need to be explained in the description. The main gaps are the undocumented connection parameter and the lack of an explicit safety/no-execution statement. For a simple EXPLAIN tool this is still minimally workable for an agent familiar with SQL.

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 0%, so the description must compensate for both parameters. It indirectly covers 'sql' by referencing SQL, but it says nothing about the 'connection' parameter or its default behavior. This leaves an agent guessing about an optional but important parameter.

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 opens with a specific verb and resource: 'show SQL execution plan (EXPLAIN) and cost.' This clearly distinguishes it from sibling tools like sql_query, which executes queries, and from other analysis tools. Even without naming alternatives, the EXPLAIN semantics make the tool's purpose 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?

The description states a concrete use case: useful before heavy queries to a remote database. This tells an agent when to prefer this tool over directly executing a query. It does not list exclusions or explicitly name alternative tools, but the guidance is clear enough.

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