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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, but the description adds genuinely new facts: the secret is encrypted, the write returns only metadata, the value is never returned, and owner is fixed at creation. It omits auth/permission requirements, which keeps it from a 5.

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?

Two compact sentences with the creation fact and the no-return guarantee front-loaded. The trailing owner sentence is mildly redundant with the schema's own owner description, so it is efficient rather than flawless.

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 nested, polymorphic 5-parameter mutation with no output schema, the description covers the essentials an agent cannot get from the schema: encryption at rest, metadata-only response, no value readback, and immutable ownership. Material-shape guidance and permission requirements are left to the schema, which is acceptable given 100% coverage.

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 100%, so the baseline is 3. The sentence about owner restates the org/project/caller choice already encoded in the oneOf discriminator and its description, and the description says nothing about the four material kinds (generic, oauth_token_set, aws_credentials, github_app_credentials) that the schema documents.

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 and resource ('Creates an encrypted secret holding one credential') and clarifies scope ('one credential'), which cleanly separates it from secrets_get/list/update/delete siblings. It never names a sibling or explicitly contrasts with them, so it stops short of a 5.

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?

Usage is only implied: the note that the value is never returned hints that reading a stored value is out of scope, and the owner immutability hints at pre-creation planning. There is no explicit when-to-use, no when-not-to-use, and no pointer to secrets_update for changing an existing secret.

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