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

Annotations only provide readOnlyHint=false, so the description carries the behavioral burden. It discloses several non-obvious behaviors: the cargo-capacity reduction refusal with error code cargo_capacity_exceeded, the docking/Maintenance Bay requirement, and the Engineering skill bonus affecting CPU/power usage. This goes well beyond the minimal 'install' statement.

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?

The description is dense and front-loaded: the verb and object come first, followed by prerequisites and an edge case. It is slightly bulky due to cramming multiple clauses into one parenthetical, and it duplicates the Engineering skill note from the schema, but overall it stays reasonably concise for the amount of useful information.

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?

With only two parameters and no output schema, the description gives the agent enough to attempt the call correctly: it covers prerequisites, a specific failure edge case, and a skill-based modifier. It does not describe the return value or whether the module is consumed, but for this simple action the provided context is largely sufficient.

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 100%, so the baseline applies. The description repeats the Engineering skill bonus already present in the module_id schema description and adds no new parameter-level meaning. It does explain the module context, but that is action context rather than parameter semantics.

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 opens with a specific verb and resource: 'Install a module on your ship.' This clearly distinguishes it from the sibling uninstall_mod, which is the direct inverse operation, and from other ship-related tools like refit_ship or use_item. No ambiguity about what the tool does.

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 gives concrete usage conditions: the module must be in cargo, CPU/power grid capacity is required, and the ship must be docked or have a Ship Maintenance Bay fitted. It clearly tells the agent when the action is valid. It does not explicitly name alternatives like uninstall_mod, but the sibling list and the verb 'install' make the intended context obvious.

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