get_available_keys

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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so the burden is lower, but the description adds genuinely useful semantics: the meaning of 'available', the fact that filter is case-insensitive substring matching, and the return shape { count, keys: [...] }.

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?

Front-loads the purpose, then the disambiguation of 'available', then the sibling routing, then the return shape. Every clause carries information an agent needs; there is no filler or repetition of the tool name.

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?

Despite no formal output schema, the description supplies the return shape, and for a zero-required-param read tool with full annotation coverage, the description leaves nothing an agent needs unresolved.

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% and the single 'filter' param is already documented as a case-insensitive substring in the schema. The description's phrasing 'optional substring filter' adds no syntax or format detail beyond that, so the 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 (list input key NAMES the engine knows) plus the domains covered (keyboard, mouse, gamepad, touch). It explicitly disambiguates 'available' as 'engine defines it, NOT unbound', which prevents the most likely misreading and separates it from find_free_input_key and list_all_input_mappings.

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?

Gives the positive use case (find the exact spelling a binding call needs, with concrete examples like 'SpaceBar' and 'Gamepad_FaceButton_Bottom') and explicitly routes elsewhere for the two adjacent jobs: find_free_input_key for unbound keys, list_all_input_mappings for already-taken keys.

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