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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety burden is offloaded. The description adds a genuinely non-obvious behavioral caveat: it silently returns no edges unless the pack ships a _graph.yaml, which prevents an agent from misreading an empty result as 'nothing related exists'.

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 tight sentences with zero filler: the core behavior and the example come first, and the critical caveat follows. Every clause earns its place, and no sentence merely restates the title.

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 no explanation, and the _graph.yaml caveat covers the main surprise. However, the description leaves edge_kinds undefined and keeps 'related guidance' vague, which is a real gap for a graph-query tool at this parameter-coverage level.

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 carry parameter meaning. It explains file_path concretely (with a worked example path) and clarifies that depth caps the number of hops, but edge_kinds is never mentioned, leaving a third of the parameters undocumented in both schema and description.

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 ('Traverses') and resource ('the EMEP knowledge graph') and clarifies the starting point (a topic file) and endpoint (related guidance). It is distinguishable from ep_search/get_guidance in mechanism, though it never names those siblings directly, so the differentiation is inferential rather than stated.

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 the scenario (go from a topic file to related guidance) but gives no explicit when-to-use versus the plausible alternatives ep_search, ep_list_topics, or get_guidance. The only constraint offered is a failure precondition (_graph.yaml), not usage routing guidance.

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