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

Annotations already declare readOnlyHint=true and destructiveHint=false, yet the description adds real context the annotations cannot carry: the three-value status semantics, the retry timing for a not-yet-ready recording, and an explicit entitlement warning that the returned URL is an access link to be shared only with someone entitled to watch. That is substantive behavioral disclosure beyond the structured fields.

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?

Roughly four short sentences, front-loaded with the return value, then the status state machine, then the sharing caveat, then the endpoint. Every sentence carries distinct information with no restatement of the title or name.

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?

There is no output schema, so the description correctly carries the return-value burden itself by explaining the URL and the status field with all three enumerated outcomes. For a single-parameter read tool this is fully complete; nothing needed to call it correctly is 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 100% and the single 'session' parameter is already documented in the schema, including a pointer to the uuid field from lessonspace_list_sessions. The description adds no format, syntax, or sourcing detail beyond that, so the baseline of 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?

The description states a specific verb and resource: it returns the playback URL of a session's recording, and it names the return field ('The playback URL of a session's recording'). The resource word 'recording' cleanly separates it from the sibling lessonspace_get_session_transcript without either schema being opened.

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?

It gives concrete usage guidance keyed to state: on 'preparing' the agent should 'ask again in a minute', and on 'no_recording' it knows no URL will exist. It does not, however, explicitly route the agent between this tool and alternatives such as lessonspace_get_session_transcript or lessonspace_get_session, so there is no when-not guidance.

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