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

With no annotations, the description carries the full behavioral burden. It discloses latency target (≤400ms), cost model (idle $0), and scope (managed SaaS, no DID sales), but omits auth requirements, error behavior, and return format. Clauses like "no DID sales" and "Own PBX optional footnote" are cryptic and add little behavioral value.

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 purpose is front-loaded in the first sentence, and the overall text is short. However, the endpoint URL is somewhat redundant, and trailing clauses such as "no DID sales" and "Own PBX optional footnote" do not earn their place and make the structure feel fragmented.

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 read tool with one required parameter and no output schema, the description gives enough to know it reads a live partial index for a call. Yet with no annotations and no output schema, it should say more about return structure and error conditions to be fully complete.

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 single call_id parameter is already fully documented in the schema. The description repeats the query parameter in a URL template but adds no syntax, format, or edge-case meaning beyond what the schema provides, so baseline 3 applies.

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?

States a specific verb and resource ("GET mid-call partial index") and clarifies the content ("accumulating facts/promises/snippets while live"). It does not explicitly differentiate from sibling tools like pbx_index_partial or pbx_facts_get, so it falls short of a 5.

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?

Implies usage context with "for whisper ≤400ms path" and "while live," and hints at cost with "Idle $0 when no live call." However, it never states when not to use this tool or names alternative siblings, leaving alternatives to inference.

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