Add a custom search engine

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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the agent knows this mutates persistent state; the description adds nothing about what gets persisted, whether the engine becomes default, or how to remove it. The 'MEASURED:' provenance and internal API details describe implementation rather than observable behavior, which is of limited value at selection time.

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?

The core definition is correctly front-loaded in the first sentence, but the remaining text spends its budget on internal source-file paths and a taxonomy of unused SearchService methods that do not help an agent invoke this tool. That is padding relative to the two parameters involved.

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 two-parameter tool with full schema coverage, no output schema, and annotations covering the mutation safety profile, the description covers what is needed to call it. The main remaining gap is the absence of any note on persistence, default-engine interaction, or reversibility for a destructive operation.

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 both params are already documented in the schema, including the {searchTerms} requirement. The description restates that formInfo takes a name plus a URL template containing {searchTerms}, confirming no additional fields are needed, but adds no syntax or format detail beyond the schema — baseline 3.

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 opening sentence gives a specific verb and resource ('Install a user-defined search engine'), which is unambiguous. It differentiates itself against internal SearchService add paths (addOpenSearchEngine, addSearchEngine, addEngineFromExtension) but never distinguishes itself from MCP siblings such as browser_search_engine or browser_get_search_engine, which is what an agent actually chooses between.

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?

It explains why this path is the simplest of four implementation options, which implies the use case (a plain name + URL-template engine), but gives no explicit when-to-use or when-not-to-use guidance against sibling tools that also touch search engines. Usage must be inferred.

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