gemini_updateCache

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

With no annotations, the description carries full burden. It discloses the mutation behavior ('Updates'), required input ('Requires the unique cache name'), and return value ('Returns the updated cache metadata'). However, it lacks details on permissions, error conditions, rate limits, or whether changes are reversible.

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 sentences, front-loaded with purpose, then requirements, then return value. Zero waste: every sentence provides essential information without redundancy.

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 mutation tool with no annotations and no output schema, the description is adequate but has gaps. It covers purpose, required input, and return type, but lacks behavioral details like permissions, side effects, or error handling. Given the complexity (update operation), more context would be beneficial.

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%, providing full documentation for all 3 parameters. The description adds minimal value beyond schema: it mentions 'TTL and/or displayName' and 'unique cache name', which the schema already covers. Baseline 3 is appropriate when schema does heavy lifting.

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?

The description clearly states the verb ('Updates'), resource ('metadata for a specific cached content resource'), and scope ('TTL and/or displayName'). It distinguishes from siblings like gemini_createCache (creates new), gemini_getCache (reads), and gemini_deleteCache (removes).

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?

The description provides clear context: 'Requires the unique cache name' and 'Updates metadata (TTL and/or displayName)'. It implies when to use (to modify existing cache metadata) but doesn't explicitly state when NOT to use or name alternatives like gemini_createCache for new caches or gemini_getCache for reading.

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