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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds value by disclosing the return shape (relevant passages plus page URLs), but says nothing about result count, ranking, or what happens with a vague query.

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, both load-bearing: the first states what it does and how, the second states what comes back. Nothing is padded or buried.

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 semantic search with fully documented schema and no output schema, the description covers purpose and return shape adequately. The one real gap is disambiguation from the two sibling docs tools, which an agent would still have to guess at.

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 a worked example for "query" and an explicit instruction for "collectionIds," so the baseline is 3. The description adds no parameter detail beyond restating that the query is natural language.

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 names a specific verb ("Search") and resource ("MSG91 documentation") plus the input style (natural-language question), so the purpose is unambiguous. It does not distinguish itself from the siblings get_msg91_api_docs or quickstart-msg91, leaving the agent to infer whether those overlap.

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?

Usage is implied by "with a natural-language question," which tells the agent the input shape but not the conditions under which this tool beats get_msg91_api_docs or quickstart-msg91. No exclusions or alternatives are named.

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