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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false, so the safety and retry profile is covered. The description adds only the hint that it operates on 'privacy-filtered project metadata' and says nothing about what completing a sync changes or whether the operation is terminal. It adds some context but no meaningful behavioral detail beyond the annotations.

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 or redundancy. It is efficient, though its brevity is part of the under-specification problem rather than purely a virtue.

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 7-parameter mutation with a nested object, required idempotencyKey and expectedVersion concurrency control, and no output schema, yet the description never explains what completing a relay sync does or what state results. For a non-destructive but non-read-only write whose core semantics are opaque, the description should do substantially more.

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%, including the nested details object, idempotencyKey retry semantics, and expectedVersion conflict behavior, so the schema carries the full parameter burden. The description's phrase 'privacy-filtered project metadata' loosely maps to the details object but adds no syntax or constraint beyond what is already documented. 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?

It names a verb (Update) and a resource (hosted relay sync completion), but 'sync completion' is not self-explanatory and the description gives no clue how it differs from the many siblings in the relay_* and *_project_sync families. An agent cannot tell from this sentence whether it finishes a relay handoff, records a status, or finalizes a sync lifecycle.

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?

There is no when-to-use guidance, no prerequisite, and no mention of alternatives such as relay_mark_sent, relay_accept, or commit_project_sync. The agent is left to infer the trigger condition for completion entirely on its own.

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