Add Subject Alias

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

Annotations already declare idempotentHint=false and destructiveHint=false, so the agent knows this is a non-idempotent but non-destructive write. The description adds a meaningful operating-mode restriction beyond the annotations, but says nothing about failure behavior (e.g., duplicate alias), permissions, or what mutation of the underlying subject's alias map means.

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?

A single front-loaded sentence with no filler; the mode restriction is appended compactly. It is efficient, though the brevity comes at the cost of the missing parameter and behavioral detail noted elsewhere.

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?

This is a mutation tool with no output schema and four undocumented parameters at 0% schema coverage, so the description carries the full explanatory burden and does not meet it. Only the mode availability is covered; scoping via context/registry and conflict behavior remain unexplained.

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% with four parameters, and the description adds no meaning for any of them. The required names alias and existing_subject are largely self-explanatory, but context and registry both default to null and their scoping behavior is entirely undocumented in both schema and description.

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 states a specific verb and resource ('Create a subject alias') and clarifies the target ('to an existing subject'), which distinguishes it from read-oriented siblings like export_subject or get_subject_config. It does not explicitly name a sibling alternative, but the operation is unambiguous.

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 parenthetical '(not available in SLIM/VIEWONLY)' gives an explicit when-not condition tied to deployment mode, which is genuinely useful. However, there is no guidance on when an alias is preferable to a context or registry-scoped entry, and no mention of prerequisites such as the alias already existing.

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