pt_fill_input

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explains the internal mechanism (walks fiber tree, calls onChangeText callback) and lists requirements, which is helpful. However, it omits potential failure behaviors (e.g., what happens if the identifier is not found, multiple matches, or if the input is uncontrolled) and does not describe return values or timeouts. This is adequate but not rich.

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 well-structured and front-loaded. The first sentence states the core purpose, followed by a bolded reliability claim, then clearly labeled REQUIREMENTS and identifier matching details. Every sentence contributes useful information without padding, and the use of headers improves scannability. Appropriate length for a tool with prerequisites.

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?

Given the tool's complexity, the description covers key contextual aspects: purpose, how it works, prerequisites, and match criteria. It does not explain error handling or return values, and there is no output schema to clarify results. Still, it is mostly complete for invoking the tool correctly, with minor gaps around edge cases.

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 is 3. The description adds value beyond the schema by specifying that the identifier is matched case-insensitively and as a partial match against accessibilityLabel, testID, or placeholder. This extra semantic detail improves understanding of the 'identifier' parameter beyond the schema's brief example.

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 clearly states the tool's function with a specific verb and resource: 'Fill a React Native TextInput by connecting to the Hermes debugger via CDP.' It distinguishes itself from siblings by emphasizing it is the 'MOST RELIABLE method for filling React Native controlled TextInput fields,' which differentiates it from pt_type_text or pt_tap.

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 provides strong usage context by listing explicit requirements: Metro dev server running, app in dev mode, and the TextInput rendered on screen. It implies when to use this tool (for controlled TextInputs) via the 'MOST RELIABLE' claim, but it does not explicitly mention alternative tools or warn against using it for non-controlled inputs. This is clear context but lacks explicit exclusions or named alternatives.

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