apply_custom_field

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

The annotations already provide destructiveHint=true, and the description goes beyond that by specifying exactly what gets destroyed: global application removes all specific object applications. This is a concrete, condition-specific behavioral disclosure rather than a generic warning. No contradiction with annotations.

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?

Three short, information-dense sentences. The main action is front-loaded, the LookupType example is relevant, and the destructive side effect is included without extra filler. Every sentence earns its place.

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 simple two-parameter mutation with no output schema and no nested objects, the description covers the core invocation knowledge: how to target an object or global scope, what determines valid targets, and the key side effect. It does not describe return values or failure modes, but the absence of an output schema lowers that expectation and the destructive note covers the main risk.

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 coverage is 100%, so the baseline is 3, but the description adds real semantic value. It explains how the custom field's LookupType governs valid ObjectId targets and elaborates the meaning of ObjectId 0 beyond the schema's simple '0 for global' by naming the destructive consequence.

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-resource pair: applying a custom field to a specific object or globally, and explains LookupType's role in determining valid target object types. This clearly distinguishes it from sibling tools like create_custom_field, add_custom_field_value, and remove_custom_field_application, which operate on creation, values, or removal rather than application.

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 clear operational context: use ObjectId 0 for global application and understand that LookupType controls what object types are applicable. However, it never explicitly names alternatives like remove_custom_field_application or list_custom_field_applications, so when-to-use-this-vs-others is implied rather than stated.

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