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

Annotations only declare readOnlyHint=false, destructiveHint=false and openWorldHint=false; the description adds real context beyond them — the email field is immutable and billed, photo removal is destructive-by-null, and OAuth-signed-in connections are required. It does not say whether omitted fields are left unchanged, which matters for a partial-update mutation.

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 tight sentences, front-loaded with what can be changed and followed by constraints and routing. Every sentence earns its place, though the theme enum duplication is slightly redundant with the schema.

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?

With no output schema, the description still covers the mutable surface, the immutable field, the auth prerequisite and cross-tool routing. The only meaningful gap is partial-update semantics — whether passing a single field leaves the others intact.

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 schema already documents name, theme and avatarUrl including the null semantics ('null to remove the photo'). The description mostly restates this, adding only the enum values and null-removal behavior that the schema itself already carries, so baseline 3 applies.

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?

Opens with a specific verb+resource ('Change your name, theme ... or photo') and enumerates the exact mutable fields with the theme enum inline. It also distinguishes itself from me_set_avatar by explicitly delegating photo uploads there, so an agent can tell the two apart without opening either 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?

Explicitly routes to the sibling tool for a new photo ('For a new photo use me_set_avatar'), states how to remove one ('pass avatarUrl null'), rules out a field ('Email cannot be changed'), and gives an auth precondition ('Signed-in (OAuth) connections only'). When-to-use, when-not-to, and the alternative are all present.

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