chembl-mcp-server

Name: chembl-mcp-server
Author: cyanheads

Server Details

Link compounds to protein targets, rank bioactivity, and look up drug mechanisms and indications.

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Status: Healthy
Uptime: 100.0% over 36 days
Last Tested: 2026-09-22 21:10
Transport: Streamable HTTP · MCP 2025-11-25
URL
Repository: cyanheads/chembl-mcp-server
GitHub Stars: 1
Server Listing: @cyanheads/chembl-mcp-server

TDQS

A4.6/5.0

Scored 2026-09-19 21:25 across 7 tools

Disambiguation5/5

Each tool targets a clearly distinct resource or stage: searching molecules vs targets, fetching bioactivities vs assay provenance vs drug info, and describing vs querying spilled data. The only adjacent pair (dataframe_describe/dataframe_query) is explicitly framed as schema discovery before SQL execution, so misselection is unlikely.

Naming Consistency5/5

All tools share the chembl_ prefix, use snake_case throughout, and follow a predictable chembl_<action>_<object> pattern such as search_molecules, get_bioactivities, and dataframe_query. The dataframe pair uses a consistent dataframe_ sub-prefix rather than a verb, but this is a minor stylistic deviation within an otherwise uniform convention.

Tool Count5/5

Seven tools is well-scoped for a ChEMBL-oriented server: discovery entry points for molecules and targets, core bioactivity and assay retrieval, drug pharmacology, plus two analysis helpers for large spilled result sets. Each tool earns its place and none feels redundant or missing from the core workflow.

Completeness4/5

The set covers the main ChEMBL workflows: resolve a target or find a molecule, retrieve bioactivities, inspect assay provenance, get drug mechanism/indication data, and analyze full result sets with SQL. Minor gaps exist—there is no dedicated single-molecule detail or target detail tool beyond search results—but agents can work around them by chaining the existing tools.

Available Tools

7 tools

chembl_dataframe_describechembl-dataframe-describeA

Read-onlyIdempotent

Inspect

List the tables and columns staged on a canvas by chembl_get_bioactivities — inspect before calling chembl_dataframe_query to write correct SQL. Returns each table with its row count, kind (table | view), and column names + types. Requires CANVAS_PROVIDER_TYPE=duckdb.

ParametersJSON Schema

Name	Required	Description	Default
`canvas_id`	Yes	Canvas ID returned by chembl_get_bioactivities (spilled: true).

Output Schema

ParametersJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`tables`	No	Tables and views staged on the canvas.

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is covered. The description adds useful behavioral context: it lists the return contents, clarifies that the data is staged by chembl_get_bioactivities, and warns about the required duckdb provider. This goes meaningfully beyond the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short sentences with no redundancy. The main action is front-loaded, the return details follow, and the environment prerequisite closes the description. Every sentence adds information an agent needs.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a one-parameter, read-only inspection tool with an output schema and safety annotations, the description is fully sufficient. It states what the tool returns, why to call it, when to call it, and a required environment condition. No critical information is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema already documents canvas_id completely (type, pattern, source, and spilled flag), so the parameter semantics are well covered structurally. The description adds context that the canvas is populated by chembl_get_bioactivities, but it does not need to add parametric detail. Baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('List') with a precise resource ('tables and columns staged on a canvas by chembl_get_bioactivities') and states the output contents (row count, kind, column names + types). It clearly differentiates itself from chembl_dataframe_query by framing itself as the inspection step before querying.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly tells the agent when to use it: 'inspect before calling chembl_dataframe_query to write correct SQL.' It also gives an environment prerequisite, CANVAS_PROVIDER_TYPE=duckdb. It does not explicitly describe when not to use it or compare against all siblings, but the sequential guidance is strong.

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

chembl_dataframe_querychembl-dataframe-queryA

Read-onlyIdempotent

Inspect

Run a read-only SQL SELECT over the bioactivity rows chembl_get_bioactivities spilled to a canvas — rank, group, dedupe, and aggregate across the FULL set, not the inline preview. Reference each staged table by the name chembl_get_bioactivities returned — bioactivities for its potency_ranked view, bioactivities_null_potency for null_potency; discover the staged tables and their columns with chembl_dataframe_describe. Compute honest aggregates here (e.g. SELECT molecule_chembl_id, MEDIAN(pchembl_value) AS med FROM bioactivities WHERE standard_type = 'IC50' GROUP BY 1 ORDER BY 2 DESC). Two independent bounds apply, each reported on its own field: truncated is true when the SQL result exceeded the canvas row cap, and rendered_rows says how many of the returned rows the markdown table holds once its character budget is reached (below row_count on a wide or long result). Page past either bound with SQL LIMIT/OFFSET — append e.g. LIMIT 500 OFFSET 500 and re-call; offsets reach rows beyond the canvas row cap. Requires CANVAS_PROVIDER_TYPE=duckdb.

ParametersJSON Schema

Name	Required	Description	Default
`sql`	Yes	A read-only SELECT against the staged tables. Reference tables by the names chembl_get_bioactivities returned.
`canvas_id`	Yes	Canvas ID returned by chembl_get_bioactivities (spilled: true).

Output Schema

ParametersJSON Schema

Name	Required	Description
`rows`	No	Result rows (capped at the canvas row limit). Each row is a column→value map.
`error`	No	Present when the call failed. Absent on success.
`row_count`	No	Number of rows materialized in this response.
`truncated`	No	True when the SQL result exceeded the canvas row cap and was truncated — the engine bounding the result set itself, not the rendering. Independent of rendered_rows; page past it with LIMIT/OFFSET.
`rendered_rows`	No	How many of those rows the markdown table in content[] holds. Below row_count when the rendered table reached its character budget — a rendering bound, INDEPENDENT of truncated: a response can be truncated:false and still render fewer rows than row_count. Re-run the same SQL with LIMIT/OFFSET to read the rows past it.

TDQS

A5/5.0

Behavior5/5

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

The description goes well beyond the annotations by disclosing result cap behavior, the meaning of truncated and rendered_rows, paging semantics, and the CANVAS_PROVIDER_TYPE=duckdb requirement. It also confirms the read-only nature, consistent with readOnlyHint=true.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is dense but front-loaded: the core purpose appears in the first sentence, followed by necessary details, an illustrative SQL example, cap semantics, and paging instructions. Every sentence adds operational value, and the structure leads the agent from purpose to invocation details.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a SQL-query tool with two parameters and rich runtime constraints, this description is complete. It covers prerequisites (spilled canvas, duckdb), table discovery, query scope, result limits, and paging, while the output schema handles return-value documentation. Nothing critical is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Although the input schema already covers both parameters, the description adds substantial meaning: how to reference staged tables, the expected SQL shape, that canvas_id must come from a spilled chembl_get_bioactivities result, and how LIMIT/OFFSET interacts with the caps. This goes far beyond the bare schema descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb and resource: 'Run a read-only SQL SELECT over the bioactivity rows chembl_get_bioactivities spilled to a canvas.' It clearly states the operations (rank, group, dedupe, aggregate) and contrasts with 'the inline preview,' which helps distinguish it from the get_bioactivities sibling.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives explicit guidance on when to use this tool: when you need full-set aggregation rather than inline preview. It names chembl_dataframe_describe as the discovery tool for staged tables and provides concrete SQL examples, plus a LIMIT/OFFSET pattern for paging beyond the canvas row cap.

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

chembl_get_assaychembl-get-assayA

Read-onlyIdempotent

Inspect

Assay provenance behind a bioactivity row: description, type (binding / functional / ADMET / toxicity), the target it measures, organism, and ChEMBL's 1–9 confidence score (9 = direct assay on the protein target, lower = homologous or indirect). Supply assay_chembl_id from a chembl_get_bioactivities row. Call this to judge whether two measurements are comparable before ranking them together.

ParametersJSON Schema

Name	Required	Description	Default
`assay_chembl_id`	Yes	ChEMBL assay ID from a bioactivity row's assay_chembl_id, e.g. "CHEMBL674637".

Output Schema

ParametersJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`organism`	No	Assay organism. Null when unspecified.
`assay_type`	No	Assay type code: B=binding, F=functional, A=ADMET, T=toxicity, P=physicochemical, U=unclassified. Null when absent.
`description`	No	Assay description text. Null when absent.
`assay_chembl_id`	No	The ChEMBL assay ID queried.
`confidence_score`	No	ChEMBL confidence score, 1–9 (9 = direct single-protein assay; lower = homologous/indirect). Null when unscored.
`target_chembl_id`	No	ChEMBL target ID the assay measures — chain to chembl_search_targets/chembl_get_bioactivities. Null when unassigned.
`assay_type_description`	No	Human-readable assay type, e.g. "Binding". Null when absent.
`confidence_description`	No	Human-readable confidence description, e.g. "Direct single protein target assigned". Null when absent.

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already cover readOnly, idempotent, and open-world behavior. The description adds valuable behavioral context by explaining the 1-9 confidence score meaning, including the 9 = direct assay distinction, which helps agents interpret results correctly.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact, front-loaded with the core resource and fields, and every sentence earns its place: what is returned, where the input comes from, and when to use the tool. No filler or redundant restatement.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a single-parameter read-only lookup with an output schema present, the description is complete. It explains the return content, the input provenance, and the intended decision-making use case, leaving no critical gap for an agent to call it correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% with a clear example, so the baseline is 3. The description adds extra semantic value by explicitly directing the agent to obtain the parameter from chembl_get_bioactivities, tying the input to a specific upstream sibling tool.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the resource ('assay provenance behind a bioactivity row') and the specific fields returned: description, type, target, organism, and confidence score. It is clearly distinct from siblings like chembl_get_bioactivities because it operates on an assay_chembl_id rather than returning bioactivity rows.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly says to call this 'to judge whether two measurements are comparable before ranking them together' and tells the agent to supply the assay_chembl_id from a chembl_get_bioactivities row. It does not explicitly name alternatives or exclusions, but the usage context is clear.

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

chembl_get_bioactivitieschembl-get-bioactivitiesA

Read-onlyIdempotent

Inspect

The flagship compound↔target bioactivity bridge: measurements for a molecule (target deconvolution / selectivity), a target (lead finding), or both together (how potently one compound hits one target). Supply at least one of molecule_chembl_id (from chembl_search_molecules) or target_chembl_id (from chembl_search_targets) — supplying both narrows to that compound–target pair, supplying neither is an error. Filter by standard_type (IC50/Ki/EC50/…), minimum potency pchembl_value_min, assay_type, and organism. Not every measurement has a derivable pchembl_value, so potency_view picks which side of that split you get: the default "potency_ranked" returns the measurements that have one, most potent first (ChEMBL sorts the rest first otherwise, which is why they are not merged), and "null_potency" returns exactly the measurements that have none. totalCount is the honest full match count across both views either way. Mixing measurement types (IC50 vs Ki) is a scientific error — set standard_type to compare like with like. A popular target carries tens of thousands of rows: results spill to a DataCanvas table (call chembl_dataframe_describe for its columns, then chembl_dataframe_query for honest aggregates across the staged set), while an inline preview answers the immediate question. Each view stages its own table (bioactivities / bioactivities_null_potency), so running both against one canvas_id lets a UNION ALL rebuild the full set. The staged table is capped at CHEMBL_MAX_SPILL_ROWS; when the cap is hit, truncated is true and the table is a bounded slice, not the complete view. The inline rows are always capped at limit, so compare that against totalCount before treating them as the whole answer. Spilling the rest requires CANVAS_PROVIDER_TYPE=duckdb; without it the inline preview is all there is.

ParametersJSON Schema

Name	Required	Description	Default
`limit`	No	Maximum rows in the inline preview. Defaults to the server default (25). The full set still spills to the canvas.
`organism`	No	Restrict to a target organism, e.g. "Homo sapiens" (case-insensitive exact match).
`canvas_id`	No	Optional canvas ID from a prior call to reuse the same canvas. Each potency_view re-stages its own table, so a second query of the SAME view REPLACES (overwrites) its prior rows — it does not append — while the other view's table is left intact, which is what lets both coexist on one canvas. Omit to mint a fresh canvas.
`assay_type`	No	Restrict to an assay type code: "B" (binding), "F" (functional), "A" (ADMET), "T" (toxicity).
`potency_view`	No	Which side of the pchembl_value presence split to retrieve. "potency_ranked" (default) returns the measurements that have a derivable pchembl_value, most potent first. "null_potency" returns exactly the measurements that have none — the rows the ranked view excludes, otherwise unreachable. The two partition the match set and stage to separate canvas tables.	potency_ranked
`standard_type`	No	Restrict to one measurement type, e.g. "IC50", "Ki", "EC50". Set this to compare potencies validly.
`target_chembl_id`	No	ChEMBL target ID (from chembl_search_targets), e.g. "CHEMBL203". Supply this, molecule_chembl_id, or both — both narrows to that compound–target pair.
`pchembl_value_min`	No	Minimum pchembl_value (−log10 molar potency), e.g. 7 keeps sub-100 nM activities. Only valid on the potency_ranked view — the null_potency rows have no pchembl_value to compare against.
`molecule_chembl_id`	No	ChEMBL molecule ID (from chembl_search_molecules), e.g. "CHEMBL941". Supply this, target_chembl_id, or both — both narrows to that compound–target pair.

Output Schema

ParametersJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`notice`	No	Guidance when no measurements matched, or how to SQL the spilled set.
`spilled`	No	True when the view exceeded the preview and was staged on the canvas.
`canvas_id`	No	Canvas ID holding the staged table — pass to chembl_dataframe_describe to list its columns, then to chembl_dataframe_query to run SQL over them. Null when canvas is disabled or nothing spilled.
`truncated`	No	True when the CHEMBL_MAX_SPILL_ROWS cap was hit before the upstream view was exhausted — the staged table is a bounded slice, NOT the complete view, so aggregates over it are a sample. Narrow the filters to bring the view under the cap.
`activities`	No	Bioactivity rows for the selected potency_view — the inline preview, or the full view when it fit without spilling.
`table_name`	No	Canvas table name holding the staged rowset, and the FROM target for chembl_dataframe_query SQL — "bioactivities" for potency_ranked, "bioactivities_null_potency" for null_potency. Null when not spilled.
`totalCount`	No	Total matching measurements upstream — the honest full count spanning BOTH potency views, before any preview cap. The staged/preview rows are the selected view of this.
`potency_view`	No	Which view these rows came from: "potency_ranked" = measurements with a derivable pchembl_value; "null_potency" = measurements with none. Re-call with the other value to reach the rest of totalCount.
`appliedFilters`	No	Filters as the server parsed them.
`canvasDisabled`	No	True when CANVAS_PROVIDER_TYPE is not duckdb, so large sets could not spill — the inline rows are a capped preview, not the full set.
`staged_row_count`	No	Rows actually registered on the canvas table. Null when nothing spilled. Below the view total when truncated is true.

TDQS

A5/5.0

Behavior5/5

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

The description discloses substantial behavior beyond the readOnly/idempotent annotations: the potency_ranked vs null_potency split, spill-to-canvas behavior, CHEMBL_MAX_SPILL_ROWS cap and truncated flag, inline limit caveat, per-view table overwrite semantics, and the CANVAS_PROVIDER_TYPE=duckdb requirement. None of this is implied by the annotations alone, and it does not contradict them.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is long but every sentence earns its place, covering usage, error conditions, scientific caveats, paging, and spill behavior. Key scoping information is front-loaded in the first sentence, and the density is justified by the tool's nine parameters and complex data-partitioning semantics.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with this complexity, the description is remarkably complete: it explains the full match count, the split views, inline vs staged results, truncation semantics, the duckdb prerequisite, and how to reconstruct the full set via a UNION ALL. The presence of an output schema means return-value specifics are covered structurally, so no critical guidance is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Even though schema coverage is 100%, the description adds critical meaning: at least one of molecule_chembl_id or target_chembl_id must be supplied, pchembl_value_min is only valid on potency_ranked, canvas_id re-stages and overwrites the same view, and potency_view maps to the presence/absence of a derivable pchembl_value. It also clarifies that both view tables can coexist on one canvas for a UNION ALL reconstruction.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens by naming the tool a 'compound↔target bioactivity bridge' and then states exactly what it returns: measurements for a molecule, a target, or both together. It immediately distinguishes this from sibling tools by framing the molecule/target relationship and by referencing the sibling search tools as the source of valid IDs.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives explicit when-to-use guidance: supply molecule_chembl_id for target deconvolution/selectivity, target_chembl_id for lead finding, or both to narrow to a pair. It also gives an explicit exclusion—supplying neither is an error—and warns against mixing measurement types, telling the agent to set standard_type to compare like with like.

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

chembl_get_drug_infochembl-get-drug-infoA

Read-onlyIdempotent

Inspect

Pharmacology for a drug (molecule): mechanism(s) of action, the molecular target(s) it acts on, action type (inhibitor / agonist / …), first-approval year, and clinical indications with the max phase reached for each. Supply molecule_chembl_id (from chembl_search_molecules). Distinct from the openfda server's label/adverse-event view — this is the curated mechanism-and-indication record. A mechanism's target_chembl_id chains into chembl_get_bioactivities for compounds hitting the same target. Each list carries its own retrieval state: an empty mechanisms or indications array means the molecule has none recorded only when the matching mechanisms_status / indications_status is "complete" — "failed" means the upstream request was rejected and the array says nothing about the molecule, and "truncated" means the page cap bounded the list at fewer rows than the matching *_total_count.

ParametersJSON Schema

Name	Required	Description	Default
`molecule_chembl_id`	Yes	ChEMBL molecule ID (from chembl_search_molecules), e.g. "CHEMBL939" for gefitinib.

Output Schema

ParametersJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`notice`	No	Disclosure of anything the two lists do not say for themselves: a list whose upstream fetch failed (so its emptiness means nothing), a list the page cap bounded, or — only when both lists came back complete and empty — that the molecule may be a research compound rather than a drug.
`max_phase`	No	Max clinical phase across indications: 4 = marketed. Null when unknown.
`pref_name`	No	Preferred drug name, e.g. "GEFITINIB". Null when unnamed.
`mechanisms`	No	Mechanisms of action. Empty is authoritative only when mechanisms_status is "complete".
`indications`	No	Clinical indications. Empty is authoritative only when indications_status is "complete".
`first_approval`	No	Year of first approval, e.g. 2003. Null when unapproved or unknown.
`mechanisms_status`	No	Retrieval state of the mechanism list. "complete" = every row ChEMBL records is present, so an empty array is a fact about the molecule. "truncated" = the single-request page cap bounded the list, so the array is a prefix of mechanisms_total_count rows. "failed" = the upstream request was rejected, so the empty array is unknown data, NOT evidence that none exist — re-call chembl_get_drug_info to retry.
`indications_status`	No	Retrieval state of the indication list. "complete" = every row ChEMBL records is present, so an empty array is a fact about the molecule. "truncated" = the single-request page cap bounded the list, so the array is a prefix of indications_total_count rows. "failed" = the upstream request was rejected, so the empty array is unknown data, NOT evidence that none exist — re-call chembl_get_drug_info to retry.
`molecule_chembl_id`	No	The ChEMBL molecule ID queried.
`mechanisms_total_count`	No	Total mechanism rows ChEMBL holds for this molecule (upstream page_meta.total_count). Exceeds the returned array length exactly when the status is "truncated". Null when the fetch failed — the count is unknown, never 0.
`indications_total_count`	No	Total indication rows ChEMBL holds for this molecule (upstream page_meta.total_count). Exceeds the returned array length exactly when the status is "truncated". Null when the fetch failed — the count is unknown, never 0.

TDQS

A4.6/5.0

Behavior5/5

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

Annotations already mark the operation read-only, open-world, and idempotent, so the description adds meaningful behavioral context beyond them: it explains retrieval states (complete, failed, truncated) and warns that empty arrays are only meaningful when the matching status is 'complete'. This is exactly the kind of non-obvious behavior an agent needs.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is front-loaded with the return payload, then gives provenance, sibling distinction, chaining, and retrieval-state semantics. It is longer than minimal, but each sentence adds necessary operational detail; the final status sentence is dense but earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a single-parameter pharmacology lookup, the description covers input source, output content, alternative views, onward chaining to bioactivities, and failure/truncation semantics. With annotations and an output schema present, nothing essential is missing for correct invocation and interpretation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The single parameter is fully documented in the schema with an example (CHEMBL939), and the description repeats the provenance ('from chembl_search_molecules') without adding new parameter-level semantics. With 100% schema coverage, baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description names the exact resource (a drug/molecule's pharmacology) and lists the concrete fields returned: mechanism(s) of action, molecular targets, action type, first-approval year, and clinical indications with max phase. It also distinguishes itself from the openfda label/adverse-event view and from chembl_get_bioactivities, so an agent can tell it apart from siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly instructs the agent to supply molecule_chembl_id from chembl_search_molecules, tells when to prefer this tool over the openfda label/adverse-event view, and explains how a target_chembl_id chains into chembl_get_bioactivities for further exploration. This gives clear when-to-use and when-not-to-use guidance.

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

chembl_search_moleculeschembl-search-moleculesA

Read-onlyIdempotent

Inspect

Discovery entry point for compounds. Find by name / ChEMBL ID / InChIKey with the default search_type=name (supply query), or run a structure search with search_type exact | similarity | substructure (supply structure as a SMILES). At least one of query or structure is required, and structure is required for the three structure modes. Returns ChEMBL ID, preferred name, canonical SMILES, formula, MW, AlogP, Lipinski violations, QED, and max clinical phase on every row; only search_type=similarity adds a Tanimoto similarity percent. Chain molecule_chembl_id into chembl_get_bioactivities or chembl_get_drug_info. A capped result carries nextCursor — pass it back as cursor with the same filters to read the next page.

ParametersJSON Schema

Name	Required	Description	Default
`limit`	No	Maximum molecules to return. Defaults to the server default (25) when omitted.
`query`	No	Search text for search_type=name — a drug name, ChEMBL ID, or InChIKey, e.g. "imatinib" or "CHEMBL25".
`cursor`	No	Opaque continuation token from a previous call's nextCursor — resumes where that page ended. Omit for the first page. Re-send the same query/structure/filters that minted it (only limit may change; it sets this page's size); redeeming it against different filters walks a different result set.
`structure`	No	SMILES string for structure search, e.g. "CC(=O)Oc1ccccc1C(=O)O". Required when search_type is exact/similarity/substructure.
`search_type`	No	name = text lookup (query); exact = exact structure match; similarity = Tanimoto ≥ threshold; substructure = contains the structure. All structure modes need `structure`.	name
`max_phase_min`	No	For search_type=name, restrict to compounds at or above this max clinical phase (e.g. 4 for marketed drugs only).
`similarity_threshold`	No	Minimum Tanimoto similarity percent for search_type=similarity (40–100; ChEMBL rejects below 40). Ignored for other modes.

Output Schema

ParametersJSON Schema

Name	Required	Description
`cap`	No	The limit that was applied.
`error`	No	Present when the call failed. Absent on success.
`shown`	No	Number of molecules returned.
`notice`	No	Guidance when nothing matched — echoes the query and suggests how to broaden.
`molecules`	No	Matching compounds (up to the limit).
`truncated`	No	True when the result was capped at the limit.
`nextCursor`	No	Opaque token for the next page — pass it back as cursor with the same filters. Absent when this page is the last one.
`totalCount`	No	Total compounds matching before the limit was applied.

TDQS

A4.7/5.0

Behavior5/5

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

Annotations carry the read-only/idempotent/open-world profile, and the description adds substantial behavior on top: the pagination contract ('A capped result carries nextCursor — pass it back as cursor with the same filters'), the mode-conditional output composition ('only search_type=similarity adds a Tanimoto similarity percent'), and per-mode input requirements. Nothing contradicts the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Roughly 100 words cover purpose, four modes, input requirements, return composition, chaining, and pagination in a logical flow. Every sentence carries operational content, and the core mode contract is front-loaded ahead of output and pagination details. Nothing is redundant with the schema.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity — 7 parameters, 4 modes, pagination, and an output schema — the description covers every decision an agent must make before calling: which mode to use, which input to supply, and how to page through results. Return-value details are already handled by the output schema, and parameter ranges by the schema; nothing needed for correct invocation is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the schema already documents every parameter; the description's key addition is the cross-parameter invariant 'At least one of query or structure is required' — a rule the schema cannot express with zero required fields. It also clarifies that similarity_threshold only matters in similarity mode. The at-least-one constraint meaningfully improves invocation correctness, pushing it just above the high-coverage baseline of 3.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific verb ('Find') against a concrete resource ('compounds' in ChEMBL) and enumerates the four search modes with their required inputs. It positions itself as the 'Discovery entry point' for molecules, which distinguishes it from sibling tools like chembl_search_targets, chembl_get_bioactivities, and chembl_get_drug_info. The scope is unambiguous and mode-specific.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description establishes when to use the tool ('Discovery entry point') and routes downstream work by instructing 'Chain molecule_chembl_id into chembl_get_bioactivities or chembl_get_drug_info.' It also states the input contract per mode (query vs structure). It does not explicitly state when-not-to-use or provide selection conditions among siblings such as chembl_search_targets, so it stops short of full exclusion criteria.

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

chembl_search_targetschembl-search-targetsA

Read-onlyIdempotent

Inspect

Resolve a protein/gene/UniProt accession to the ChEMBL target ID that chembl_get_bioactivities needs for the target→leads workflow. Supply at least one of accession (UniProt, e.g. P00533), gene_symbol (e.g. EGFR), or query (free-text name); filter further by organism and target_type. Returns each target with its type, organism, and component UniProt accessions + gene symbols. A UniProt accession from the uniprot/protein server is the most precise input. A capped result carries nextCursor — pass it back as cursor with the same filters to read the next page.

ParametersJSON Schema

Name	Required	Description
`limit`	No	Maximum targets to return. Defaults to the server default (25) when omitted.
`query`	No	Free-text name match against the target preferred name, e.g. "kinase" or "growth factor receptor".
`cursor`	No	Opaque continuation token from a previous call's nextCursor — resumes where that page ended. Omit for the first page. Re-send the same accession/gene_symbol/query/filters that minted it (only limit may change; it sets this page's size); redeeming it against different filters walks a different result set.
`organism`	No	Restrict to a source organism, e.g. "Homo sapiens" (case-insensitive exact match).
`accession`	No	UniProt accession of a target component, e.g. "P00533". The most precise resolver — from the uniprot/protein server.
`gene_symbol`	No	Gene symbol of a target component, e.g. "EGFR" (case-insensitive exact match).
`target_type`	No	Restrict to a target class, e.g. "SINGLE PROTEIN" or "PROTEIN COMPLEX".

Output Schema

ParametersJSON Schema

Name	Required	Description
`cap`	No	The limit that was applied.
`error`	No	Present when the call failed. Absent on success.
`shown`	No	Number of targets returned.
`notice`	No	Guidance when no target matched — echoes the filters and suggests how to broaden.
`targets`	No	Matching targets (up to the limit).
`truncated`	No	True when the result was capped at the limit.
`nextCursor`	No	Opaque token for the next page — pass it back as cursor with the same filters. Absent when this page is the last one.
`totalCount`	No	Total targets matching the filters before the limit was applied.

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent, and open-world behavior; the description adds useful pagination behavior via nextCursor/cursor and explains the result contents (type, organism, component accessions and gene symbols). No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact, front-loaded with purpose, then input requirements, return contents, precision guidance, and pagination. Every sentence adds useful information with no filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given a complete input schema, an output schema, and annotations covering read-only/idempotent behavior, the description covers everything needed to invoke the tool correctly: purpose, required input modes, optional filters, precision ordering, and pagination handling.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3. The description adds meaningful semantic guidance beyond the schema: at least one of three inputs is required, UniProt accession is the most precise resolver, and the cursor must be reused with the same filters. This elevates it above baseline.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb and resource: 'Resolve a protein/gene/UniProt accession to the ChEMBL target ID'. It also names the downstream consumer, chembl_get_bioactivities, which clearly differentiates this resolver from its siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description states the workflow context ('target→leads workflow') and gives concrete input guidance: supply at least one of accession, gene_symbol, or query, and optionally filter by organism and target_type. It does not explicitly list when-not-to-use alternatives, but the purpose is clear enough to make selection unambiguous.

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

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

7 tool updatesSep 19, 2026
- Changedchembl_dataframe_describe1 field changed
  - addedInput schema / properties / canvas_id / pattern
```
Added value: +"^[A-Za-z0-9_-]{10}$"
```
- Changedchembl_dataframe_query1 field changed
  - addedInput schema / properties / canvas_id / pattern
```
Added value: +"^[A-Za-z0-9_-]{10}$"
```
- Changedchembl_get_assay14 fields changed
  - removedOutput schema / properties / assay_type / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / assay_type / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / assay_type_description / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / assay_type_description / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / confidence_description / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / confidence_description / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / confidence_score / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / confidence_score / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / description / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / description / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / organism / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / organism / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / target_chembl_id / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / target_chembl_id / type
```
Added value: +[
+  "string",
+  "null"
+]
```
- Changedchembl_get_bioactivities43 fields changed
  - addedInput schema / properties / canvas_id / pattern
```
Added value: +"^[A-Za-z0-9_-]{10}$"
```
  - removedOutput schema / properties / activities / items / properties / assay_description / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / assay_description / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / assay_type / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / assay_type / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / molecule_pref_name / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / molecule_pref_name / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / pchembl_value / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / pchembl_value / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / relation / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / relation / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / standard_relation / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / standard_relation / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / standard_type / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / standard_type / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / standard_units / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / standard_units / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / standard_value / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / standard_value / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / target_organism / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / target_organism / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / target_pref_name / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / target_pref_name / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / type / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / type / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / units / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / units / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / activities / items / properties / value / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / activities / items / properties / value / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / appliedFilters / properties / assay_type / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / appliedFilters / properties / assay_type / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / appliedFilters / properties / organism / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / appliedFilters / properties / organism / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / appliedFilters / properties / pchembl_value_min / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / appliedFilters / properties / pchembl_value_min / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / appliedFilters / properties / standard_type / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / appliedFilters / properties / standard_type / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / canvas_id / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / canvas_id / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / staged_row_count / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / staged_row_count / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / table_name / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / table_name / type
```
Added value: +[
+  "string",
+  "null"
+]
```
- Changedchembl_get_drug_info22 fields changed
  - removedOutput schema / properties / first_approval / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / first_approval / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / indications / items / properties / efo_term / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / indications / items / properties / efo_term / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / indications / items / properties / max_phase_for_ind / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / indications / items / properties / max_phase_for_ind / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / indications / items / properties / mesh_heading / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / indications / items / properties / mesh_heading / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / indications_total_count / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / indications_total_count / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / max_phase / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / max_phase / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / mechanisms / items / properties / action_type / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / mechanisms / items / properties / action_type / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / mechanisms / items / properties / mechanism_of_action / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / mechanisms / items / properties / mechanism_of_action / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / mechanisms / items / properties / target_chembl_id / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / mechanisms / items / properties / target_chembl_id / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / mechanisms_total_count / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / mechanisms_total_count / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / pref_name / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / pref_name / type
```
Added value: +[
+  "string",
+  "null"
+]
```
- Changedchembl_search_molecules22 fields changed
  - removedOutput schema / properties / molecules / items / properties / alogp / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / molecules / items / properties / alogp / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / molecules / items / properties / canonical_smiles / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / molecules / items / properties / canonical_smiles / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / molecules / items / properties / full_molformula / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / molecules / items / properties / full_molformula / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / molecules / items / properties / max_phase / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / molecules / items / properties / max_phase / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / molecules / items / properties / molecule_type / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / molecules / items / properties / molecule_type / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / molecules / items / properties / mw_freebase / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / molecules / items / properties / mw_freebase / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / molecules / items / properties / num_ro5_violations / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / molecules / items / properties / num_ro5_violations / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / molecules / items / properties / pref_name / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / molecules / items / properties / pref_name / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / molecules / items / properties / qed_weighted / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / molecules / items / properties / qed_weighted / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / molecules / items / properties / similarity / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / molecules / items / properties / similarity / type
```
Added value: +[
+  "number",
+  "null"
+]
```
  - removedOutput schema / properties / molecules / items / properties / standard_inchi_key / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / molecules / items / properties / standard_inchi_key / type
```
Added value: +[
+  "string",
+  "null"
+]
```
- Changedchembl_search_targets8 fields changed
  - removedOutput schema / properties / targets / items / properties / components / items / properties / accession / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / targets / items / properties / components / items / properties / accession / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / targets / items / properties / organism / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / targets / items / properties / organism / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / targets / items / properties / pref_name / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / targets / items / properties / pref_name / type
```
Added value: +[
+  "string",
+  "null"
+]
```
  - removedOutput schema / properties / targets / items / properties / target_type / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
  - addedOutput schema / properties / targets / items / properties / target_type / type
```
Added value: +[
+  "string",
+  "null"
+]
```

7 tool updatesAug 25, 2026

Changedchembl_dataframe_describe6 fields changed

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "tables"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `canvas_disabled`: Called while CANVAS_PROVIDER_TYPE is not duckdb, so no canvas exists. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "canvas_disabled"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required
```
Removed value: -[
-  "tables"
-]
```

Changedchembl_dataframe_query6 fields changed

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "rows",
+      "row_count",
+      "rendered_rows",
+      "truncated"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `canvas_disabled`: Called while CANVAS_PROVIDER_TYPE is not duckdb, so no canvas exists. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "canvas_disabled"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "rows",
-  "row_count",
-  "rendered_rows",
-  "truncated"
-]

Changedchembl_get_assay6 fields changed

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "assay_chembl_id",
+      "description",
+      "assay_type",
+      "assay_type_description",
+      "target_chembl_id",
+      "organism",
+      "confidence_score",
+      "confidence_description"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode.",
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "assay_chembl_id",
-  "description",
-  "assay_type",
-  "assay_type_description",
-  "target_chembl_id",
-  "organism",
-  "confidence_score",
-  "confidence_description"
-]

Changedchembl_get_bioactivities6 fields changed

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "activities",
+      "totalCount",
+      "potency_view",
+      "spilled",
+      "canvas_id",
+      "table_name",
+      "staged_row_count",
+      "truncated",
+      "canvasDisabled",
+      "appliedFilters"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `missing_filter`: Neither molecule_chembl_id nor target_chembl_id was supplied, so the query had nothing to scope to. `contradictory_potency_filter`: pchembl_value_min was supplied alongside potency_view \"null_potency\", whose rows have no pchembl_value for the floor to compare against — the combination can only ever match zero measurements. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "missing_filter",
+            "contradictory_potency_filter"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "activities",
-  "totalCount",
-  "potency_view",
-  "spilled",
-  "canvas_id",
-  "table_name",
-  "staged_row_count",
-  "truncated",
-  "canvasDisabled",
-  "appliedFilters"
-]

Changedchembl_get_drug_info6 fields changed

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "molecule_chembl_id",
+      "pref_name",
+      "max_phase",
+      "first_approval",
+      "mechanisms",
+      "mechanisms_total_count",
+      "mechanisms_status",
+      "indications",
+      "indications_total_count",
+      "indications_status"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode.",
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "molecule_chembl_id",
-  "pref_name",
-  "max_phase",
-  "first_approval",
-  "mechanisms",
-  "mechanisms_total_count",
-  "mechanisms_status",
-  "indications",
-  "indications_total_count",
-  "indications_status"
-]

Changedchembl_search_molecules6 fields changed

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "molecules",
+      "totalCount",
+      "truncated",
+      "shown",
+      "cap"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `missing_input`: Neither query nor structure was supplied, or a structure search_type was chosen without a structure. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "missing_input"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "molecules",
-  "totalCount",
-  "truncated",
-  "shown",
-  "cap"
-]

Changedchembl_search_targets6 fields changed

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "targets",
+      "totalCount",
+      "truncated",
+      "shown",
+      "cap"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `missing_input`: None of query, accession, or gene_symbol was supplied. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "missing_input"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "targets",
-  "totalCount",
-  "truncated",
-  "shown",
-  "cap"
-]

2 tool updatesAug 13, 2026

Changedchembl_search_molecules3 fields changed

addedInput schema / properties / cursor

Added value: +{
+  "description": "Opaque continuation token from a previous call's nextCursor — resumes where that page ended. Omit for the first page. Re-send the same query/structure/filters that minted it (only limit may change; it sets this page's size); redeeming it against different filters walks a different result set.",
+  "type": "string"
+}

changedOutput schema / properties / molecules / items / properties / similarity / description

Previous value: -"Tanimoto similarity percent (0–100) to the query structure. Present only on similarity/substructure search."New value: +"Tanimoto similarity percent (0–100) to the query structure. Present only on search_type=similarity results; on every other search_type the key is absent, not null."

addedOutput schema / properties / nextCursor

Added value: +{
+  "description": "Opaque token for the next page — pass it back as cursor with the same filters. Absent when this page is the last one.",
+  "type": "string"
+}

Changedchembl_search_targets2 fields changed

addedInput schema / properties / cursor

Added value: +{
+  "description": "Opaque continuation token from a previous call's nextCursor — resumes where that page ended. Omit for the first page. Re-send the same accession/gene_symbol/query/filters that minted it (only limit may change; it sets this page's size); redeeming it against different filters walks a different result set.",
+  "type": "string"
+}

addedOutput schema / properties / nextCursor

Added value: +{
+  "description": "Opaque token for the next page — pass it back as cursor with the same filters. Absent when this page is the last one.",
+  "type": "string"
+}

2 tool updatesAug 13, 2026

Changedchembl_dataframe_query3 fields changed

addedOutput schema / properties / rendered_rows

Added value: +{
+  "description": "How many of those rows the markdown table in content[] holds. Below row_count when the rendered table reached its character budget — a rendering bound, INDEPENDENT of truncated: a response can be truncated:false and still render fewer rows than row_count. Re-run the same SQL with LIMIT/OFFSET to read the rows past it.",
+  "type": "number"
+}

changedOutput schema / properties / truncated / description

Previous value: -"True when the SQL result exceeded the canvas row cap and was truncated."New value: +"True when the SQL result exceeded the canvas row cap and was truncated — the engine bounding the result set itself, not the rendering. Independent of rendered_rows; page past it with LIMIT/OFFSET."

changedOutput schema / required

Previous value: -[
-  "rows",
-  "row_count",
-  "truncated"
-]New value: +[
+  "rows",
+  "row_count",
+  "rendered_rows",
+  "truncated"
+]

Changedchembl_get_drug_info8 fields changed

changedOutput schema / properties / indications / description

Previous value: -"Clinical indications. Empty when none are recorded."New value: +"Clinical indications. Empty is authoritative only when indications_status is \"complete\"."

addedOutput schema / properties / indications_status

Added value: +{
+  "description": "Retrieval state of the indication list. \"complete\" = every row ChEMBL records is present, so an empty array is a fact about the molecule. \"truncated\" = the single-request page cap bounded the list, so the array is a prefix of indications_total_count rows. \"failed\" = the upstream request was rejected, so the empty array is unknown data, NOT evidence that none exist — re-call chembl_get_drug_info to retry.",
+  "enum": [
+    "complete",
+    "truncated",
+    "failed"
+  ],
+  "type": "string"
+}

addedOutput schema / properties / indications_total_count

Added value: +{
+  "anyOf": [
+    {
+      "type": "number"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "description": "Total indication rows ChEMBL holds for this molecule (upstream page_meta.total_count). Exceeds the returned array length exactly when the status is \"truncated\". Null when the fetch failed — the count is unknown, never 0."
+}

changedOutput schema / properties / mechanisms / description

Previous value: -"Mechanisms of action. Empty when none are recorded."New value: +"Mechanisms of action. Empty is authoritative only when mechanisms_status is \"complete\"."

addedOutput schema / properties / mechanisms_status

Added value: +{
+  "description": "Retrieval state of the mechanism list. \"complete\" = every row ChEMBL records is present, so an empty array is a fact about the molecule. \"truncated\" = the single-request page cap bounded the list, so the array is a prefix of mechanisms_total_count rows. \"failed\" = the upstream request was rejected, so the empty array is unknown data, NOT evidence that none exist — re-call chembl_get_drug_info to retry.",
+  "enum": [
+    "complete",
+    "truncated",
+    "failed"
+  ],
+  "type": "string"
+}

addedOutput schema / properties / mechanisms_total_count

Added value: +{
+  "anyOf": [
+    {
+      "type": "number"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "description": "Total mechanism rows ChEMBL holds for this molecule (upstream page_meta.total_count). Exceeds the returned array length exactly when the status is \"truncated\". Null when the fetch failed — the count is unknown, never 0."
+}

changedOutput schema / properties / notice / description

Previous value: -"Guidance when no pharmacology was found — the molecule may be a research compound, not a drug."New value: +"Disclosure of anything the two lists do not say for themselves: a list whose upstream fetch failed (so its emptiness means nothing), a list the page cap bounded, or — only when both lists came back complete and empty — that the molecule may be a research compound rather than a drug."

changedOutput schema / required

Previous value: -[
-  "molecule_chembl_id",
-  "pref_name",
-  "max_phase",
-  "first_approval",
-  "mechanisms",
-  "indications"
-]New value: +[
+  "molecule_chembl_id",
+  "pref_name",
+  "max_phase",
+  "first_approval",
+  "mechanisms",
+  "mechanisms_total_count",
+  "mechanisms_status",
+  "indications",
+  "indications_total_count",
+  "indications_status"
+]

7 tool updatesAug 13, 2026
- First observedchembl_dataframe_describe
- First observedchembl_dataframe_query
- First observedchembl_get_assay
- First observedchembl_get_bioactivities
- First observedchembl_get_drug_info
- First observedchembl_search_molecules
- First observedchembl_search_targets

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