explain_query

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering safety and side-effects. The description adds that it returns an execution plan and restricts input to SELECT or WITH queries, which is beyond the annotations. However, it does not describe edge behaviors like failure mode or cluster-specific aspects, though those are minor given the safety profile.

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?

A single sentence that front-loads the core action (return execution plan) and supplies the only necessary constraint (SELECT/WITH). There is no filler or redundant information, making it highly scannable and complete.

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?

The tool is simple (one required parameter), has an output schema, and is fully covered by annotations (read-only, idempotent, non-destructive). The description provides all essential context for invoking it: what it returns, for what kind of input, and the execution plan format. Nothing obscure remains unexplained.

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?

With schema description coverage at 0%, the description must compensate. It does so by qualifying that the 'sql' parameter must be a 'SELECT or WITH query' for Impala, which is meaningful semantic guidance beyond the bare schema field type. It could be more explicit about the exact grammar or quoting requirements, but it sufficiently clarifies the expected input.

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 ('Return') and a specific resource ('Impala execution plan (EXPLAIN)'), and narrows the scope to 'SELECT or WITH query'. This clearly distinguishes it from siblings like 'query' (executes a query) and 'get_ddl' (returns DDL), so an agent can tell what the tool does without opening schemas.

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 implies when to use the tool (when you want an Impala execution plan rather than execution), but it never explicitly says 'use this instead of query when...' or names any sibling alternatives. There are no exclusions or conditions beyond the SELECT/WITH scope, so the guidance is implied rather than explicit.

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