scan_sessions

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral detail: per-group failure reporting, coverage range, and resume offset, plus the explicit scope limitation of only scanning specified sessions. This exceeds the annotation baseline without contradicting it.

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 description is two compact sentences that front-load the main purpose, use case, and key constraint. Every clause carries information with no redundancy, making it highly efficient.

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?

With 10 parameters, no output schema, and only 0% schema description coverage, the description is incomplete. It explains the main filtering logic but omits semantics for offsets, context windows, and per_session_limit, and does not describe the full response structure beyond failures, coverage, and offset. An agent would need to infer or experiment to use it correctly.

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 0%, and the description only hints at a subset of parameters. It mentions time, keywords, any/all, and sender IDs, which maps to start_time, end_time, keywords, match_mode, and sender_ids, but leaves offsets, context_before/after, per_session_limit, and session_ids unexplained. Given 10 parameters and no schema descriptions, the description should compensate more comprehensively.

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 states a specific verb (batch read), resource (specified sessions), and filtering dimensions (time, keyword any/all, sender ID). It also distinguishes itself from siblings by explicitly noting it does not scan unspecified groups, making its scope unmistakable.

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 a clear use case ('multi-group topic, information, and resource aggregation') and a constraint ('does not scan unspecified groups'), implying when to choose this over broader search tools. It stops short of naming specific alternative tools, but the context is sufficient for an agent to infer its niche.

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