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

With no annotations, the description carries the burden well: it discloses that the child is confined to its budget/expiry/allowlist, that child spend also draws down the parent's daily limit, and it names the exact failure code 'parent_daily_limit'. It omits what is returned (the child key/secret) and whether approvalAboveCents escalates asynchronously.

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?

Front-loaded with the core action, then progressively adds constraints and the important parent-daily-limit caveat. Dense but nearly every clause carries real information; the sentence is long and could be split for readability.

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 7-parameter credential-minting tool with no annotations and no output schema, the description leaves the return value unexplained — an agent does not know it receives a child key secret that must be captured. The permission and budget semantics are otherwise adequately covered.

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 every parameter, including units and constraints (cents, max 30 days, allowlist entry syntax), is already documented in the schema. The description restates the same four fields without adding format or interaction detail beyond the parent/child budget coupling.

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 ('Delegate a scoped child key for a worker') and enumerates the key's dimensions (budget, expiry, daily limit, allowlist). It is clearly distinguishable from siblings like list_subagents and revoke_subagent, which operate on keys rather than creating them.

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?

Gives an explicit precondition ('Only top-level agents can delegate') and points to lifecycle management ('revoke it any time', i.e. use revoke_subagent). It stops short of naming sibling alternatives or stating when NOT to mint a child versus using a topup/upgrade link.

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