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

Annotations already declare destructiveHint=true, idempotentHint=false and readOnlyHint=false, so the safety profile is covered there. The description adds genuinely new behavior: partial/patch update semantics and the non-obvious sentinel that 'a null description clears it'. It stops short of warning that changing values or validation can affect existing contact data.

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 sentences, each doing distinct work: scope of changeable fields, the immutability constraint with a remediation, and the partial-update plus null-clearing rule. Front-loaded with no padding.

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 destructive, non-idempotent mutation tool with no output schema and 7 undocumented parameters, the description covers immutability and patch behavior well but omits attribute_display_type entirely and says nothing about the downstream impact of changing values/validation on contacts already using the attribute.

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 0% across 7 parameters, so the description must carry the load. It clarifies attribute_values ('values') and regex_pattern/regex_cue ('validation') plus the null-clears semantics for attribute_description, but never mentions attribute_display_type (an 8-value enum), attribute_id, or max-length/item limits.

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 gives a specific verb ('Change') plus the resource and enumerates exactly which fields are mutable (display name, description, values, validation). It also states what is immutable, which separates it cleanly from create_custom_attribute and delete_custom_attribute.

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 supplies an explicit exclusion and routes the agent elsewhere: 'the attribute_key and the model cannot change: create a new attribute instead.' It also clarifies patch semantics ('only the fields you pass change'), but gives no general when-to-use framing or prerequisites (e.g. needing to read the attribute first).

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