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

Annotations already declare readOnly/idempotent/non-destructive and closed-world, so safety needs no restating. The description adds that results are bounded by two ISO timestamps and lists id/day/time/status, but says nothing about ordering, pagination, or inclusive/exclusive boundary 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?

Three short sentences, each doing distinct work: usage trigger, behavior, and exclusion routing. The use-case framing comes first, which is the right front-loading for a query tool.

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 an output schema present, the description needn't detail return values, and for a two-required-param read tool this is close to sufficient. Only edge-case range semantics (timezone, inclusivity) are missing.

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%, so the description must carry the load, and it does identify from/to as ISO times defining the range. It does not clarify timezone, whether boundaries are inclusive, or what happens when from > to.

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 ('Lists their sessions') plus the scope ('between two ISO times'). It explicitly separates itself from get_today and, by naming sessions with ids/status, from get_session detail retrieval.

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?

Gives concrete user-intent triggers ('what's coming up this week or next', 'what they did on other days') and an explicit exclusion with a named alternative ('Do not use for today's session; use get_today'). Nothing is left to inference.

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