Change a field

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

Beyond the annotations (destructiveHint=true, idempotentHint=true), the description explains exactly why the operation is destructive: options REPLACES allowed values and records holding a removed value keep it as stale text. It also discloses the platform-side refusal on incompatible type changes, that the field key is immutable, and that the response is structuredContent {field}, all of which the annotations do not convey.

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 front-loaded sentences plus a return-value clause, with the highest-risk fact (options replaces values, leaving stale text) surfaced early. No redundant restatement of the name or title.

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 10-parameter destructive mutation with an output schema, the description covers partial-update semantics, the destructive edge case, the type-change refusal, immutability of the key, and the return shape. Nothing an agent needs to call it correctly is missing.

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; the description earns above that by adding meaning the schema lacks, notably that options overwrites rather than merges and that a type change is rejected when existing values do not fit. It does not otherwise elaborate on individual parameters such as ai_prompt's credit cost or schema_id's requirement, which the schema already handles.

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 ("Changes one field of an object by field_id") and immediately tells the agent where field_id comes from (heliyos_objects_get), which separates it from heliyos_fields_create and heliyos_fields_delete without opening another schema.

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?

It states the partial-update contract ("What you leave out is kept") and the preconditions for a type change, which tells the agent how to call it safely. It does not explicitly name the alternative tools (fields_create/fields_delete) or the when-not condition, so it falls short of a full routing statement.

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