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

readOnlyHint=true already covers the safety profile, so the bar is lower. The description adds meaningful content context: the response covers protocol deltas and ChargerDojo module coverage gains, which is the only signal about return shape since no output schema exists. Depth/pagination of the diff is not disclosed, keeping it out of the top band.

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 short sentences, front-loaded with the verb and resource. The second sentence largely restates the first in question form ('what changes when I move from...'), which is mildly redundant but still clarifies intent rather than padding.

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?

For a two-enum read-only tool, the description covers purpose, direction of comparison, and what the result contains, which compensates for the missing output schema. It leaves open the diff granularity and whether invalid/unreleased version pairs are handled, but nothing an agent needs to invoke it correctly is absent.

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?

Both parameters are fully described in the schema with enums and examples, so schema coverage is effectively 100%. The description only implicitly reinforces the directional semantics ('move from one ... to another'); it adds no format or constraint detail beyond the schema. Baseline 3 applies.

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 ('Compare two OCPI versions') and then scopes what the comparison covers: protocol changes between them plus which modules ChargerDojo gained. That distinguishes it from chargerdojo_compare_run and from chargerdojo_get_ocpi_version without requiring the agent to open either schema.

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 line 'Answers: what changes when I move from one OCPI version to another' gives a clear usage context, effectively an upgrade-migration question. It stops short of naming exclusions or alternatives (e.g. use get_ocpi_version for a single version, list_ocpi_versions to see what is available).

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