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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered structurally. The description adds the useful facts that validation happens pre-execution and that the graph is an ExecGraphSnapshot, but it says nothing about what checks are performed or how a failing graph is reported.

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?

Three short sentences, front-loaded with the purpose, then shape, then construction path. No filler; each sentence carries information. It is slightly dense in its second sentence but remains readable.

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?

Given an output schema, annotations, and a single nested object parameter, the description covers purpose, required input shape, and input sourcing. It could add a word on failure semantics or the validate_node boundary, but nothing critical is missing for correct invocation.

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 coverage is 100%, so the baseline is 3, but the description earns above baseline by specifying the nested shape the schema leaves opaque (nodes carry id, type, config; connections carry from/to). That is real meaning beyond the additionalProperties:true object in the schema.

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 gives a specific verb+resource pair ("Validate a pipeline graph") plus a timing qualifier ("before running"), so the agent knows exactly what the tool does. It does not explicitly contrast itself with the close sibling pipeline.validate_node, leaving that distinction to inference.

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 supplies clear pre-flight context ("before running") and names two concrete ways to obtain the input, catalog.template(id).train or catalog.nodes(). However, it never says when to use this whole-graph validator instead of pipeline.validate_node or protocol.validate, which are the most confusable siblings.

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