hybrid_query

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description goes further by disclosing concurrency behavior, server-side join/aggregation, truncation-safe failure (fails rather than reporting misleading totals), and the absence of a cross-database snapshot guarantee. These are meaningful traits not derivable from structured fields.

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?

Four short sentences, purpose front-loaded, no filler. The dense trailing exclusion sentence packs three distinct caveats, which is efficient though slightly compressed.

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 need not be described. For a complex nested plan, the description covers the plan's shape and key caveats adequately, with the remaining gap being per-source field semantics that the description only gestures at.

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 carries the burden and largely does: it explains that the single plan param holds named sources, equijoin specs keyed by source.field, and optional group_by/metrics. It omits how per-source fields (database, operation, filter/params/pipeline) shape a source, so compensation is good but not complete.

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: run concurrent SQL/MongoDB reads, then join and aggregate server-side. This is a distinctive hybrid capability that reads clearly as its own thing. It does not name the sibling tools it overlaps with (query_sql, aggregate_documents, find_documents), so an agent must infer the boundary itself.

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?

It gives construction guidance (named sources, inner/left equijoins on source.field keys) and a negative clause (no writes, no NL planning, no cross-database snapshot guarantee). However it never says when to prefer this over the single-source siblings like query_sql or aggregate_documents, leaving the routing decision to inference.

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