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

Annotations already flag destructiveHint=true and idempotentHint=true, but the description adds real operational context: the refusal of REMOVED, the meaning of PAUSED vs ENABLED, and the explicit warning that re-enabling means the keyword 'serves again and can spend.' That spend consequence is precisely the kind of impact an agent needs before calling a destructive-flagged 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?

Front-loaded with the one-line purpose, then the deletion constraint and the serve/spend consequence, then Args and Returns. Every sentence carries information; the only filler is the trailing 'Tools revision' line, which is trivial.

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?

Covers the mutation semantics, optionality, and units an agent needs for a 5-parameter mutation. Since an output schema exists, the Returns line is mildly redundant, and the description does not say whether both status and bid can be changed in one call or what happens if neither is supplied.

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%, so the description carries the full burden and does: it identifies customer_id as numbers-only without hyphens, explains ad_group_id/criterion_id roles, enumerates the legal status values (ENABLED, PAUSED) where the schema has a bare string, and defines cpc_bid_micros as micros of the account's currency. This is material meaning the schema does not supply.

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?

Names a specific verb ('Updates') and resource ('a keyword') plus the two mutable fields (status, bid). It is clearly distinguishable from add_keywords and from the sibling set_*_status / update_ad_status tools, which operate on different resources.

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 a hard exclusion: 'It never deletes: status REMOVED is refused,' so an agent knows not to attempt deletion here. It lacks an explicit pointer to which sibling to use for removal or for creating keywords, so it falls short of the when-to-use/when-not/alternative triad.

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