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

Beyond readOnlyHint=false, the description discloses failure behavior with a concrete error code (cargo_capacity_exceeded) and its triggering condition, plus the Engineering skill reduction that changes effective CPU/power cost. It does not say whether a failed install leaves state untouched or how to recover the module, but the mutation profile is well covered.

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 action is front-loaded and the parenthetical groups all constraints efficiently in one place. The Engineering skill-bonus sentence duplicates the schema's module_id description, which is the main piece of removable text.

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-parameter mutation with no output schema, the description supplies the preconditions, the failure mode, and the cost-modifier semantics an agent needs before calling it. Only the post-call state (does the module disappear from cargo?) is left unspecified.

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?

With 100% schema coverage across only two parameters, the schema already documents module_id and session_id fully. The description's cargo-requirement note marginally informs module_id's meaning, but the Engineering-skill sentence simply repeats the schema's parameter text, so it adds little.

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?

It states a specific verb and resource ("Install a module on your ship") and the effect on ship fitting is unambiguous. The opposite sibling uninstall_mod is implied by the verb, but no sibling is named explicitly, so differentiation is inferred 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?

Preconditions are enumerated precisely: module must be in cargo, CPU/power capacity required, and location must be docked, a Ship Maintenance Bay, or co-located with an undocked faction-mate's bay ship. There is no explicit 'do not use when' or pointer to uninstall_mod/refit_ship as alternatives, which keeps it short of a 5.

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