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

With no annotations, the description must carry the behavioral burden. It discloses that the tool selects and returns relevant tools rather than executing them, and explains the intended client-side effect. However, it does not describe return format, side-effect guarantees, or any constraints like rate limits or query semantics beyond the basic routing behavior.

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?

Two sentences with the core purpose front-loaded in 'Semantic tool router' and an immediate elaboration. The reference to 'MCP optimisation literature' is slightly ornamental but does reinforce the meta-tool identity. No wasted words overall.

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 simple two-parameter tool without an output schema, the description gives enough context to understand the tool's role and input. The missing return-form detail is partially covered by the 'inject 3 schemas' phrase, which implies the return includes tool definitions. Slightly more explicit output behavior would push this to a 5.

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 baseline is 3 and the description need not restate parameters. It does add context for 'query' (natural-language intent) but contributes no additional meaning for 'limit' beyond the schema's own default. The description's value here is marginal.

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 defines the tool as a 'semantic tool router' that takes a natural-language intent and returns the most relevant tools from the server. This specific verb-object pair ('return relevant tools') distinguishes it from the many domain-specific calculator/advisor siblings, and the meta-tool framing makes its role unambiguous.

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 states the context of use: when a client needs to reduce the number of tool schemas injected (from 27 to 3) by querying a natural-language intent. It does not explicitly list when not to use it or mention alternatives, but the use case is clear enough from the 'instead of 27' phrasing.

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